Good Corporate Governance is essential to increase the confidence of investors. Corporate Governance can provide effective protection for stockholders and facilitate effective monitoring. The empirical study intends to investigate determinant Good Corporate Governance and the effect of implementation corporate governance toword firm value in banking sector. Corporate Governance practical is measured by composite index Good Corporate Governance. Samples of this study are banking companies listed in Indonesia Stock Exchange during 2008 -2012. This research data from annual reports obtained from the Indonesian Stock Exchange website, the Indonesian Banking Directory and Indonesian Capital Market Directory (ICMD). The analytical method used is multiple linear regression . This research gives some evidences that determinants of implementation quality of Corporate Governance are size and ownership concentration. Good Corporate Governance showed significant and positive relationship to firm value. The test result of indirect influence of ownership concentration, growth to firm value with intervening variables (GCG) is not significant