隨著企業財務弊案接連發生，導致投資人信心潰散，迫使人們不得不重視公司治理之議題，而自願性揭露即為公司治理機制下資訊透明度的表徵中相當重要的環節。公司治理機制的好壞將影響自願性揭露的水準。因此，本研究欲以公司治理內外部機制的角度，探討影響自願性揭露的因素。首先，本研究將所採用之揭露索引表先製作為問卷，以國內財務分析師為問卷發放對象，之後再根據所填答之結果增減揭露索引表之內容，以作為揭露評分項目，再依據各上市公司自願性揭露程度，瞭解各公司之公司治理機制的有效性。結果發現：獨立董（監）事比率愈高，自願性揭露程度愈高；董事長兼任總經理會傷害資訊揭露程度，此外，亦發現獨立董（監）事的存在能夠降低董事長兼任總經理對自願性揭露程度所帶來之傷害；在董事長兼任總經理的情況下，隨著家族成員佔董（監）事席次比率的提高，會加深公司於自願性揭露上之不足。 最後，本研究探討自願性揭露程度與公司績效間之關係，並且考慮變數間之內生性關係，而分別利用一般最小平方法與二階段最小平方法，期望解決過去研究中僅使用一般最小平方法所可能出現之估計偏誤之問題。實證結果顯示，隨著自願性揭露程度之提升，公司之財務績效（資產報酬率與每股盈餘）與市場績效（股票報酬率與Tobin’s Q）皆會隨著提高，甚至對於後續績效之影響亦甚明顯。此結果顯示出為公司於提供資訊揭露上，能帶來激勵之效果。 It is commonly agreed that there were numbers of accounting scandals that were not only the result of a loss in investor confidence but, more importantly, of a lack of effective corporate governance. Voluntary disclosure plays a major role in corporate governance. The purpose of this study is to examine the relationship between the effectiveness of corporate governance mechanisms, voluntary disclosure, and firm performance. First, this research’s disclosure index items were made as questionnaire and then sent to financial analysts in Taiwan. The purpose of this survey was to determine users’ perceptions of the usefulness of various voluntary disclosure items. According to the each listed company’s disclosure sore to observe the effective corporate governance mechanisms. The result shows that the level of voluntary disclosure increases if percentage of independent board director increases and the firms that have one individual who serves as both chairman and chief executive officer are more likely to have a lower extent of disclosure. Moreover, we also find that the negative association between CEO duality and the level of voluntary disclosure is weaker when the firms have a higher percentage of independent board directors. Finally, this research adopts ordinary least squares, and two stage least squares to test the association between the level of voluntary disclosure and firm’s performance. The results support the following hypotheses. The level of voluntary disclosure has significantly positive effect on firm’s value. This result will encourage the firms to improve the level of voluntary disclosure.