It’s expected in efficient capital markets that all of available information, reflect rapidly in the price of securities. If entering accounting information to the market cause to changes of share price, this information relate to the share value and have information content. In this paper, the effect of conservatism on the value relevance, has researched.In order to doing this research, information of 110 companies accepted in Tehran Stock Exchange market (TSE), during 7 years course between 2004 to 2010, have used. In order to measuring to conservatism of two criteria, asymmetric timeliness of earnings, and the accruals-based criteria, has used. And in order to measuring the value relevance, two Price and Return criteria has used. The results of the paper indicate that the value relevance of accounting information has no significant difference, in companies with high and low degree of conservatism. In the other words, conservatism degree of companies, has no effect on information contents of their accounting items. By doing additional examination, these results partly adjusted, because it can realized from this examinations that companies with moderate and high conservatism degree, offered relatively, more relevant accounting information to share value.