Since the composition of the capital structure and corporate governance is one of the factors that can maximize corporates' value and contributes to their survival in today's competitive condition, the main objective of this study is to review the effect of capital structure on additional return with the effect of corporate governance quality as moderating variable at the Tehran Stock Exchange listed companies. To achieve this goal, the data of 103 companies during the financial periods from 2003 to 2014 is used. The results show that capital structure has a positive and significant effect on additional return and has a negative and significant effect on corporate governance quality. But between corporate governance quality and additional return no significant relationship was found. Corporate governance quality has not moderating effect on relationship between capital structure and additional return.