本研究旨在探討公司治理與動態資本結構之間的關係，以及產品市場競爭對此關係的影響。 第一篇文章探討公司治理品質如何影響動態資本結構。本篇文章同時考慮負債的「接管防禦」與「懲罰」效果，對最適資本結構調整速度的影響。我們的實證結果發現，雖然低負債(underlevered)和高負債(overlevered)公司，皆呈現公司治理品質愈差，調整速度愈慢的結果，但原因並不相同。以低負債且弱治理的公司來說，因負債所扮演的懲罰角色帶來的成本，高於使用負債作為接管防禦工具所帶來的利益，因此公司傾向減少負債的使用，並以較緩慢的速度朝向目標資本結構調整。但就高負債弱治理的公司而言，因面臨較嚴重的接管威脅，為了驅逐潛在的掠奪者，公司選擇增加負債的使用，而不願調降其負債水準至目標值，因此也降低了資本結構的調整速度。 第二篇文章主要探討產品市場競爭在公司治理品質與動態資本結構關係中所扮演的角色。文獻中已有許多研究探討市場競爭對經理人的怠惰行為的影響。然而，到目前為止，仍然沒有文獻研究產品市場競爭程度的高低如何影響公司治理與資本結構調整速度之間的關係。我們的文章因此補足目前研究文獻不足之處。實證結果顯示，公司在競爭的狀態下，更願意以追求股東財富極大化為其目標，此舉也因此提升公司資本結構朝向最適目標值調整的速度。除此之外，我們的實證結果亦發現在一個高度市場競爭的環境下，弱治理與強治理公司之間調整速度的差距會縮小。 / This study contains two essays on the relationship between corporate governance on capital structure dynamics, and how production market competition affects this relation. Essay 1: Corporate Governance and the Dynamics of Capital Structure: New Evidences The effects of corporate governance on optimal capital structure choices have been well documented, though without offering empirical evidence about the impact of corporate governance quality on the adjustment speed toward an optimal capital structure. This study simultaneously considers two effects of debt originating from agency theory—the takeover defense and the disciplinary effects of debt—on the speed of adjustment to the optimal capital structure. Corporate governance has a distinct effect on the speed of capital structure adjustment: weak governance firms that are underlevered tend to adjust slowly to the optimal capital structure, because the costs of the disciplinary role of debt outweigh the benefits of using debt as a takeover defense tool. Although, overlevered weak governance firms also adjust slowly, they do so because they are reluctant to decrease their leverage toward the target level to deter potential raiders, especially if they face a serious takeover threat. Therefore, this study finds that both overlevered and underlevered firms with weak governance adjust slowly toward their target debt levels, though with different motivations. Essay 2: Corporate Governance, Product Market Competition, and Dynamic Capital Structure The importance of product market competition for analyzing managerial slack or the impact of corporate governance on capital structure decision has been widely discussed. However, prior studies pay little attention to center on the impact of market competition on the relationship between corporate governance quality and capital structure dynamics. This paper thus fills this gap in the literature. Our study finds that competition makes firms with weak governance have stronger incentive to maximize shareholders’ wealth and thus increase their adjustment speed toward their target leverage. Moreover, the difference in the adjustment speeds between weak and strong governance firms become smaller when firms operate in highly competitive industries.