This study aimed to investigate empirically the effect of voluntary disclosure of financial information and CSR disclosure on earnings response coefficient at manufacturing companies that listing on the Indonesian Stock Exchange in 2008-2009. This study using a disclosure index advanced by Botosan (1997) to measure the scope of voluntary disclosure financial information and CSR Index, adapted from research Sembiring (2005) to measure the scope of CSR disclosure and the earnings response coefficient is measured with regression of abnormal return with unexpected earnings ± 5-day at window period from the date of publication of annual report. This study uses multiple regression analysis and correlation analysis of 24 annual report data’s, stock price index’s and manufacturing company listed for year period 2008-2009. The results showed that partially voluntary disclosure of financial information has no significant positive influence on earnings response coefficient while for CSR disclosure has significant negatively influence on earnings response coefficient. Furthermore, voluntary disclosure of financial information and CSR disclosure simultaneously did not affect the earnings response coefficient.