Opportunistic behaviors of earnings management practices increases the lack information asymmetry, that results the accounting conservatism as a solution for reducing the agency cost by accountants. Accountants use earnings management to reduce information asymmetry through the conservatism. The purpose of this paper is to examine mediating effect of conservatism on the relationship between information asymmetry and earnings management. For this purpose 117 of the companies listed in Tehran Stock Exchange during 2009-2013 is selected as a sample and their data was analyzed using the EVIEWS software. The findings indicate that conservatism has mediator effect between information asymmetry and earnings management. These findings besides suggesting the complexity of the relationship between financial structures can be used by investors and policymakers in the stock exchange.