Corporate governance is the system by which organizations are directed and controlled. It relates to the way in which companies are governed, with a particular emphasis on the relationship between shareholders and managers. The main intellectual foundation of corporate governance is agency theory. The need to set up a system of corporate governance arises from the relationship of agency that binds shareholders and managers. A good system of corporate governance, should make it possible to limit conflicts of interest between shareholders and management. This research is intended to study the impact of Good Corporate Governance (GCG) towards financial performance. Corporate Governance Perception Index (CGPI) as the proxy of GCG and company’s financial performance are measured using Return on Equity (ROE) and Tobin’s Q. This research is a quantitative research and the source is secondary data obtained from companies that are listed in Indonesia Stock Exchange (IDX) and GCG ranking held by IICG during the period 2012-2015. By using the purposive sampling method, a total of 40 samples are obtained. The analysis model used in this research is the simple linear regression model. The result of this research indicates that Good Corporate Governance has an insignificant positive impact on Return on Equity (ROE) and Good Corporate Governance has a significant negative impact on Tobin’s Q.