本研究以Gompers et al.(2003)建構之G-index為併購防禦措施多寡的代理變數與Brown and Caylor(2006)建構之G-score為公司治理綜合指標，探討公司治理結構、代理成本、公司資金成本三者間的關係，並探究代理成本是否會成為兩者之間的中介變數。在統計分析方法上，本研究採用混合迴歸(pooled OLS)、追蹤資料模型(Panel data model)、Fama-MacBeth(1973)橫斷面迴歸、中位數迴歸(median regression)、兩階段最小平方法( Two-Stage Least Square)、順序多重分類模型(ordered logit/ordered probit)來進行研究分析。研究結果說明如下：

一、公司治理與資金成本
當公司購併防禦措施越多時(Gindex越大)，會提高公司權益資金成本；但卻能降低公司負債成本。當公司治理越健全時(Gscore越大)，能夠降低公司權益與負債成本。

二、代理成本與資金成本
代理成本越高時，即資產報酬率波動程度越大、營運費用比率越大、資產周轉率越小時，則公司的權益與負債資金成本則越高。

三、公司治理與代理成本
當公司購併防禦措施越多時(Gindex越大)，具有保障管理階層的工作的功能，使得管理階層能夠專心致力於經營公司，因此降低整體的代理成本。當公司治理越健全時(Gscore越大)，資訊不對稱越嚴重，內部管理者越容易傷害股東與債權人，造成代理衝突的增加，因此增強代理成本對權益與負債資金成本之影響。

四、公司治理、代理成本與資金成本之中介效果
公司治理機制並非完全透過對代理成本的降低的控制來影響企業的資金成本。綜合各模型所得較一致性的結果顯示，公司治理機制變數，並不因代理成本變數加入而失去對資金成本的影響力，顯示兩者同為解釋資金成本的重要因素。

In this paper, we want to examine the impact of corporate governance mechanisms on agency cost and cost of capital. We employ the shareholder rights governance score of Gompers, Ishii and Metrick (2003) to be a proxy variable for set of antitakeover devices and use the corporate governance score of Brown and Caylor(2006) to be a proxy variable for set of governance mechanisms. Pool ordinary least square, panel data model , Fama-Macbeth regression , median regression, two-stage least square, ordered logit, and ordered probit are employed to do the analysis. This study can be summarized：

(1) Relation between corporate governance mechanisms and the cost of capital
Antitakeover device (Gindex) has positive effect on cost of equity capital, but has negative effect on cost of debt capital. Corporate governance score(Gscore) has negative effect on cost of equity capital and cost of debt capital.

(2) Relation between agency cost and the cost of capital
Operating risk (StdROA) and operating expense ratio(Exp) have positive effect on cost of capital. Asset turnover ratio (Atturn) has negative effect on cost of capital.

(3) Relation between corporate governance mechanisms and agency cost
Antitakeover device (Gindex) has negative effect on agency cost. Corporate governance score(Gscore) has negative effect on agency cost.

(4)Mediating effect
The mediating effects of agency cost is only slightly significant.

參考書籍

Woolridge, J. "Econometric Analysis of Cross Section and Panel Data. "
Greene,W.H. "Econometric Analysis 5th. "
Stock,J.H. and Watson M.W. "Introduction to Econometrics. "
Kim,K.A. and Nofsinger,J.R. "Corporate Governance"
葉銀華，李存修，柯承恩，公司治理與評等系統，商智文化
Berle, A. and G. Means. "The modern corporation and private property." MacMillan, New York, N. Y. (1932)

中文期刊

王文宇，非合意併購的政策與法制-以強制收購與防禦措施為中心，月旦法學雜誌，第一二五期，頁155-175 (2005)。

朱德芳，論重整中公司之公司治理問題-以當事人利害衝突與重整法之目的為核心，兼論債權人於公司治理中之功能與地位，東吳法律學報，第十七卷第二期，頁193-248 (2005)。

朱德芳，效率、併購與公司治理-以敵意併購法規範為核心，中原財經法學，第十七期，頁196-259 (2006)。

任慶宗、劉士銘、尹靖遠，網絡中心性與知識創新-知識資本之中介效果，2005年第三屆『管理思維與實務』學術研討會論文集。

林黎華，我國強制收購制度規範內容與適用疑義之探討（下），集保月刊，第一三八期，頁17-30 (2005)。

林文政、陳慧娟、周淑儀，台灣資訊電子產業之企業人力資本、新資與組織績效之關聯性研究-薪資中介效果之檢驗，東吳經濟商學學報，第五十九期，頁57-100 (2006)。

柯承恩，我國公司治理體系之問題與改進建議(上)及(下)，會計研究月刊，第173 期，頁75-83 (2000)。

洪榮華、陳香如、林慧珍，公司治理機制對創新、多角化策略及公司績效之影響-研發密集產業之實證，中山管理學報，第十五卷第一期，頁37-60 (2007)。
許崇源、陳瑞斌，公司治理與權益資金成本之關聯性研究，2005年第三屆『管理思維與實務』學術研討會論文集。

喬友慶、葉凱莉、別蓮蒂，顧客滿意度衡量與估計之研究-線性迴歸模型與Ordered Probit/Logit模型之比較，企業管理學報，第五十五期，頁1-23 (2000)。

中文學位論文

王雯靜，財務政策、控制股東之股權結構與財務危機間關係之研究，國立中央大學企業管理碩士班 (2004)。

李心怡，控制權與所有權偏離對代理成本與無形資產之影響，國立嘉義大學管理碩士班 (2005)。

林詠捷，公司治理指標對股價報酬之影響分析：以購併事件為代理成本因子，國立台灣大學財務金融研究所 (2004)。

林惠玲，代理成本、盈餘屬性與資金成本之關係，輔仁大學會計學系碩士班 (2005)。

周時如，企業融資決策之從眾行為探討，世新大學財務金融碩士班 (2004) 。

洪 駿，公司治理機制對代理成本控制之研究-以台灣上市公司為對象，淡江大學會計學碩士班 (2004)。

莊佩蓁，公司治理與股價關聯性之研究-採用Ohlson模型，東吳大學企業管理碩士班 (2007)。

簡佩玉，員工分紅政策對高階經理人留任及公司績效之影響研究-以台灣地區上市電子產業為例，東吳大學國際貿易學系碩士在職專班 (2007)。

廖秀梅，董事會結構特性與公司績效關係之研究－探討台灣家族控制企業因素的影響，國立台北大學會計學研究所 (2004)。

楊士奇，台灣上市公司影響代理問題因素之探討，國立中山大學財務金融學系碩士班 (2004)。

游采熒，盈餘品質與資金成本之關聯性，國立台灣大學會計學研究所 (2004)。

駱美琪，委託書爭奪對股東財富影響之再探討-從公司治理角度，國立中興大學財務金融研究所 (2006)。

劉彥皇，公司敵意併購防禦措施之研究，中原財經法律研究所 (2007)。

蔣婉萍，反敵意接管策略之法律研究-以美國先進經驗為例，來看台灣未來發展，國立中央大學產業經濟研究所 (2004)。

英文參考文獻

Ahmed, A. S., B. K. Billings, R. M. Morton, and M. Stanford-Harris."The Role of Accounting Conservatism in Mitigating Bondholder-Shareholder Conflicts over Dividend Policy and in Reducing Debt Costs." The Accounting Review, 77 (2002),
867-890.

Amihud, Y., and B. Lev."Risk Reduction as a Managerial Motive for Conglomerate Mergers." Joumal of Economics, 12 (1981), 605-618.

Agrawal, A., and C.R.Knoeber. "Firm Performance and Mechanism to Control
Agency Problems between Managers and Shareholders." Journal of Financial and
Quantitative Analysts, 31(3) (1996), 377-397.

Anderson, M., R.Banker, and S. Ravindran. "Executive Compensation in the Information Technology Industry. "Management Science, 46 (2000),530-547.

Anderson, R., S. Mansi., and D. Reeb. "Founding Family Ownership and the Agency Costs of Debt."Joumal of Einancial Economics, 68 (2003), 263-285.

Ang,J.S., A.C.Rebel, and W.J.Lin. "Agency Costs and Ownership Structure." Journal of Finance, 55 (2000), 81-106.

Ashbaugh-Skaife, H., D. W.Collins, and R. LaFond. "The Effects of Corporate Governance on Firms’Credit Ratings." Journal of Accounting and Economics, 42 (2006), 203–243

Ashbaugh-Skaife, H., D. W.Collins, and R. LaFond. "Corporate governance and the cost of equity capital." SSRN Working Paper (2005)

Autore, D.M., T. Kovacs, and V.Sharma "Do analyst recommendations reflect shareholder rights?" Journal of Banking & Finance, 33(2)(2009),193-202.

Bacon, J., and J. F. Brown. "Corporate Directorship Practices: Role Selection
and Legal Status of the Board. " New York: The Conference Board. (1973)

Baron, R. M., and D. A. Kenny. "The Moderator- Mediator Variable Distinction in Social Psychological Research: Conceptual, Strategic, and Statistical Consideration. " Journal of Personalityand Social Psychology, 51(6) (1986), 1173-1182.

Baker, M., and J. Wurgler. "Market Timing and Capital Structure." The Journal of Finance ,57(1) (2002), 1-32.

Bebchuk, L., A. John Coates IV and Guhan Subramanian. "The Powerful Antitakeover Force of Staggered Boards Theory, Evidence & Policy." Stanford Law Review, 54 (2002), 887-951.

Bebchuk, Lucian A., John C. Coates IV and Guhan Subramanian. "The Power of Takeover Defenses. " Working paper, Harvard Law School and NBER. 2003.

Bebchuk, L., and A. Cohen."The Costs of Entrenched Boards," Journal of Financial Economics, 78 (2007), 409-433.

Bebchuk, L., A., Cohen, and A.Ferrell."What Matters in Corporate Governance? " Working Paper Harvard Law School.(2006)

Bhagat, S., and B. Black."The Uncertain Relationship Between Board Composition and Firm Performance," Business Lawyer, 55(1999), 921-963.

Bhojraj, S.,and P. Sengupta. "Effects of Corporate Governance on Bond Ratings and Yields: TheRole of Institutional Investors and Outside Directors." Journal of Business, 76 (2003), 455-475.

Billett, M.,D. King, and D. Mauer. "Bondholders Wealth Effects in Mergers and Acquisitions: New Evidence from Ihe 1980s and 1990s." Joumal of Finance. 59 (2004), 107-135.
Black, B.,H. Jang,and W. Kim. "Does Corporate Govemance Affect Firm Value? Evidence from Korea." Working Paper, KDI School of Public Policy and Management (2006).

Boehren, O, and B.A. Odegaard. " Governance and Performance Revisited. " Working Paper (2003)

Botosan, C. A. "Disclosure level and the cost of equity capital." Accounting Review, 72 (1997), 323-349

Bradley, M., G.A.,Jarrel, and E.H. Kim. "On the Existence of an Optimal Capital Structure: Theory and Evidence. " Journal of Finance ,39(1984), 857-878.

Brown, L.D.,and M.L.Caylor. "Corporate Governance and Firm Performance." Journal of Accounting and Public Policy, 25 (2006), 409–434

Causholli,M. and W.R. Knechel. "Lending Relationships, IPOs, and the Effect of Auditor Quality on the Cost of Debt." SSRN Working Paper, (2006).

Chava,S., D.Livdan, and A.Purnanandam. "Do shareholder rights affect the cost of bank loans? " SSRN Working Paper. (2008)

Chen, C.R., and T.L., Steiner. "Managerial Ownership and Agency Conflicts: A Non- linear Simultaneous Equation Analysis of Managerial Ownership, Risk Taking,
Debt Policy and Dividend Policy." The financial Review, 34 (1999) ,119-136.

Chen, K. C. W., Chen, Z. H. and J. K. C. Wei.. "Disclosure, Corporate Governance, and the Cost of Equity Capital: Evidence from Asia’s Emerging Markets." SSRN Working Paper. (2003)

Chen, K. C. W., Chen, Z. H. and J. K. C. Wei.. "Disclosure, Corporate Governance, and the Cost of Equity Capital: Evidence from Asia’s Emerging Markets. " SSRN Working Paper. (2004)

Chen, Z.H. "Agency cost and the Effect of Corporate Governance on the Implied Cost of Capital." WorkingPaper, Hong Kong University of Science and Technology (2005).

Chung, Kee H., "Asset Characteristic And Corporate Debt Policy: An Empirical Test", Journal of Accounting and Economics, 16(1993), 83-98.

Claessens, S., M. P. Dooley, and A. Warner. "Portfolio Capital Flows: Hot or Cold? " World Bank Economic Review, 9(1)(1995), 153–74.

Core, J., R. Holthausen, and D. Larcker. "Corporate Govemance, Chief Executive Office Compensation, and Firm Performance." Journal of Einancial Economics, 51 (1999), 371-406.

Core,J.E., W.R. Guay, and T.O. Rusticus. "Does Weak Governance Cause Weak Stock Returns?An Examination of Firm Operating Performance and Investors’ Expectations" Journal of Finance, 2 (2006),665-687.

Cremers, M.,V. Nair, and C. Wei. "The Impact of Shareholder Control on Bond- holders." WorkingPaper, Yale School of Management (2004).

Conyon, M. and R. Freeman. "Shared Models of Compensation and FirmPerformance: UK Evidence" Working Paper, University ofPennsylvania and London School of Economics (2000)
Daily,C.M. and D.R.,Dalton. "Borads of Directors, Leadership and Structure：Control and Performance Implications." Entrepreneurship Theory and Practice
17 (1993) 65-81.

Datta,S, M. Iskandar-Datta, and A.Patel. "Bank monitoring and the pricing of corporate public debt." Journal of Financial Economics, 51 (1999) 435-449.

Demsetz, H. and K. Lehn. "The Structure of Corporate Ownership：Causes and
Consequences "Journal of Political Economy, 93(1985) 1155-1177.

DeAngelo, H., and E. Rice. "Antitakeover Charter Amendments and Stockholder Wealth." Joumal of Einancial Economics, 11 (1983), 329-359.

Dhaliwal, D.S., M.Erickson, M.M.Frank,and M. Banyi. "Are Shareholder Dividend Taxes on Corporate Retained Earnings Impounded in Equity Prices? " Journal of Accounting and Economics, 35(2003)

Easton, P. " P/E Ratios, PEG Ratios, and Estimating the Implied Expected Rate of Return on Equity Capital. " The Accounting Review, 79(2004), 73-95.

Eichholtz,P., B.Bauer, and N. Kok. "Corporate Governance and Performance:The REIT Effect. "Working Paper (2007)

Elliott,J.A., and D.B. Kennedy." Estimation and Prediction of Categorical Models in Accounting Research" Journal of Accounting Literature, 7(1988), 202-242.

Epps, R.W., and S. J.Cereola. "Do Institutional Shareholder Services (ISS)
Corporate Governance Ratings Reflect Acompany’s Operating Performance?" Critical Perspectives on Accounting, 19 (2008), 1135–1148.

Fama, E., and M. Miller. The Theory of Einance. Hinsdale, IL: Dryden Press (1972).

Fama E., and J. MacBeth. "Risk, Return, and Equilibrium: Empirical Tests." Journal of Political Economy, 81 (1973), 67-105.

Fama,E., "Agency Problems and the Informativeness of Earnings." Journal of
Political Economy, 88(1980), 288-307.

Fama, E., and K. French. "The Cross-Section of Expected Stock Returns" Journal of Finance, 47(1992), 472-465.

Fama, E., and K. French. "Common Risk Factors in the Retums of Stocks and Bonds." Journal of Einancial Economics, 33 (1993), 3-56.

Fama, E., and K. French."Industry Costs of Capital."Journal of Financial Economics, 43 (1997), 153-193

Fama, E.F.,and M.C.Jensen."Separation of ownership and control. " Journal of Law and Economics ,26(1983), 301-325.

Florackis,C.,and A.Ozkan. "Agency Costs and Corporate Governance Mechanisms: Evidence for UK Firms." International Journal of Managerial Finance,(2008)

Francis, J., R. LaFond, P. Olsson, and K. Schipper." The Market Pricing of Accruals Quality. " Journal of Accounting and Economics, 39 (2005b), 295-327.

Garmaise M.J.,and Liu J. "Corruption, Firm Governance, and the Cost of Capital. "
Working Paper, University of California (2005).

Gebhardt, R.William, Charles M. C. Lee and Bhaskaran Swaminathan "Toward an implied cost of capital." Journal of Accounting Research, 39(2001), 135–176.

Ghosh ,A. and Prem C. Jain ."Financial Lev Changes Associated with Corporate Mergers" Journal of Corporate Finance, 6(4), (2000), 377-402.

Giannetti, M., Koskinen, Y. "Investor Protection and the Demand for Equity."SSRN Working Paper,(2005).

Gompers, P.; J. Ishii; and A. Metrick. "Corporate Govemance and Equity Prices." Quarterly Joumal Of Economics, 118 (2003), 107-155.

Graham, J.R., M.L. Lemmon, and J.S. Schallheim. "Debt, Leases, Taxes, and the Endogeneity of Corporate Tax Status. " Journal of Finance, 53(1998), 131–161.

Hartzell, J. C., and L. T. "Starks.Institutional Investors and Executive Compensation. " The Journal of Finance, 58 (2003), 2351-2374.

Harris, E. "Antitakeover Measures, Golden Parachutes, and Target Firm Shareholder Welfare." RAND Journal of Economics, 21 (1990), 614-625.

Haugen, R. and L. Senbet. "Resolving The Agency Problems of External Capital through Options" Journal of Finance, 36 (1981),629-648.

Hausman, J. A. "Specification tests in econometrics." Econometrica, 46(1978), 1251-1271.

Healy P.M., Krishna G. Palepu and R. Rubback "Does Mergers Improve Corporate PerformanceJournal of Financial Economics, (1992)

Himmelberg, C., G. Hubbard, and D. Palia. "Understanding the Determinants of Managerial Ownership and the Link between Ownership and Performance. " Journal of Financial Economics, 53(1999), 353-84.

Huang, H.,D.Collins, and C.S.Agnes Chen "Shareholder rights and the cost of equity capital. " SSRN Working Paper (2004).

Jensen M., and W. Meckling. "Theory of the Firm: Managerial Behavior, Agency Costs and OwnershipStructure." Journal of Einancial Economics, 3 (1976), 305-360.

Jensen, M., and R. Ruback. 'The Market for Corporate Control: The Scientific Evidence." Joumal ofEinancial Economics, 11 (1983), 5-50.

Jensen, M. "Agency Costs of the Free Cash Flow, Corporate Finance and Takeovers." American Economic Review, 76 (1986), 323-329.

Jensen, Michael C. & Warner, Jerold B. "The Distribution of Power among Corporate Managers, Shareholders, and Directors," Journal of Financial Economics, 20(1-2) (19 88), 3-24.

Jiraporn, P., and Ning,Y. " Dividend Policy, Shareholder Rights, and Corporate Governance " Journal of Applied Finance, 30 (2006), 947-963.

Jiraporn,P., and Kim, J.C. "Dividend Policy and Corporate Governance Quality " SSRN WorkingPaper,(2008).

Karpoff, J.M., P.H. Malatesta,and R.A. Walkling."Corporate Governance and Shareholder Initiatives: Empirical Evidence." Journal of Financial Economics, 42(1996), 365-395.

Klock, M., S. Mansi, and W. Maxwell. "Does Corporate Governance Matter to Bondholders. "Journal of Financial and Quantitative Analysis, 40 (2005), 693-719.

Koenker, R. and G. W. Bassett. "Regression Quantiles." Econometrica, 46(1)(1978), 211-244.

La Porta, R., Lopez-de-Silanes, F., Shleifer, A. "Corporate Ownership around the World. "Journal of Finance, 54, (1999) 471-517.

La Porta, R., Lopez-de-Silanes, F., Shleifer, A., Vishny, R. " Legal Determinants of External Finance". Journal of Finance, 52, (1997) 1131-1150.

La Porta, R., Lopez-de-Silanes, F., Shleifer, A., Vishny, R. "Law and Finance. " Journal of Political Economy, 106, (1998) 1113-1155.

La Porta, R., Lopez-de-Silanes, F., Shleifer, A., Vishny, R. "The Quality of Government. "Journal of Law, Economics and Organization, 15, (1999a) 222-279.

Lambert, R., Larcker, D., and R. Verrecchia. "Portfolio Considerations in Valuing Executive Compensation. "Journal of Accounting Research, 29 ( 1991), 129-149.

Lombardo, D. and M. Pagano. "Legal Determinants of The Return on Equity" Working Paper, (2000)

Maddala, G.S. "Limit-Dependent and Qualitative Variables in Econometrics."
New York: Cambridge University Press. (1983)

Manne. H. "Mergers and the Market for Corporate Control. " Journal of Political Economy, 73 (1965), 110-120.

Mcknight,P.J and C.Weir. "Agency Costs, Corporate Governance Mechanisms and Ownership Structure in Large UK Publicly Quoted Companies: A Panel Data Analysis"The Quarterly Review of Economics and Finance, 49 (2009) ,139-158

Minton,B.A. and C. Schrand. "The Impact of Cash Flow Volatility on Discretionary Investment and the Costs of Debt and Equity Financing."Journal of Financial Economics, 54 (1999), 423-460.

Modigliani, F. and M. H. Miller."The Cost of Capital, Corporate Finance, and the Theory of Investment." American Economic Review, 48(1958), 261-97.

Morck, R., A. Shleifer, and R.W. Vishny . "Management ownership and market valuation：An empirical analysis. " Journal of Financial Economics, 20(1988),293 -315.

Morsman J, E. "Commercial loan structuring. Journal of Commercial Bank Lending ." ,58(1986), 2–20.

Olson, J. and B. Juettner-Nauroth ."Expected EPS and EPS Growth as Determinants of Value" Review of Accounting Studies, 10 (2005),349–365.

Organization for Economic Cooperation and Development. OECD principles of corporate governance. OECD Paris (1999).

Ortiz-Molina,H."Executive Compensation and Capital Structure: The Effects of Convertible Debt and Straight Debt on CEO pay" Journal of Accounting and Economics, 43(2007), 69-93

Parrino, R., and M. Weisbach. "Measuring Investment Distortions Arising from Stockholder-Bondholder Conflicts." Joumal of Einancial Economic. 53 (1999), 3-42.

Petersen, M.A.,and R.G. Rajan. "The Benefits of Lending Relationships: Evidence from Small Business Data." Journal of Finance, 49(1994), 3–37.

Peel,M.J.,and M.M.H.Coode, and L.A.Moutinho. "Estimating Cosumer Satisfaction :OLS Versus Ordered Probability Models" International Journal of Commerce amd Management, 8(1980),109-131.

Pittman, J. A. and S. Fortin. "Auditor Choice and the Cost of Debt Capital for Newly Public Firms. " Journal of Accounting and Economics, 37 (2004), 113-136.

Pound, J. "Proxy Contests and the Efficiency of Shareholder Oversight. " Journal of Financial Economics, 20 (1988), 237-265.

Rosenstein , S., and J. H. Waytt. " Outside Directors, Board Independence and
Shareholder Wealth. " Journal of Financial Economics, 26 (1990), 175-191.

Sengupta,P. "Corporate Disclosure Quality and Cost of Debt" The Accounting Review, 73(4) (1998), 459-474.

Shieifer, A., and L. Summers. "Breach of Tmst in Hostile Takeovers." In Corporate Takeovers:Causes and Consequences, A. J. Auerbach, ed. Chicago, IL: Univ. of Chicago Press (1988).

Shieifer, A., and R. Vishny. "A Survey of Corporate Govemance." Joumal of Einance, 52 (1997),737-783.

Singh, M.,and Davidson,W. A. "Agency Costs, Ownership Structures and Corporate Governance Mechanisms. " Journal of Banking and Finance, 27 (2003), 793–816.

Smith, C. and R. Stulz. "The Determinants of Firm's Hedging Policies. " Journal of Financial and Quantitative Analysis, 20 (1985), 391-405.

Sorensen, D.E. "Characteristics of merging firms." Journal of Economics and Business, 52(5) (2000), 423-433.

Stein, J. "Takeover Threats and Managerial Myopia." Joumal of Political Economy, 96 (1988), 61-80.

Stultz, Ren, "Globalization of Equity Markets and the Cost of Capital." Working Paper Fisher College of Business, Ohio State University (1999a)

Yermack, D. "Higher market valuation of companies with a small board of directors. " Journal of Financial Economics 40(1996),85 –212.

Zahra, S. A. and J. A. Pearce. "Boards of Directors and Corporate Financial Performance: A Review and Integrative Model." Journal of Management, 15(1989), 291-334.

Zhou, X. "Understanding the Determinants of Managerial Ownership and the Link between Ownership and Performance: Comment " Journal of Financial Economics, 62 (2001),559-71.