Earnings management has inverted the main objective of financial reporting through the distortion of the actual economic performance of companies and prevented the complete transfer of information to market. Given the importance of subject of research, incentives that cause earnings management have been reviewed from various aspects. The main purpose of this research is to examine the relationship between competition in industry and pricing power at product market and earnings management in the companies listed in Tehran stock exchange. For this, modified Lerner index was used to measure pricing power and three middle Lerner indices including industry, reverse number of firms in the industry, four-firm concentration ratio were used as the indices of competition in industry. To measure earnings management, Modified Jones Model was used. The statistical population consists of all the firms listed in Tehran stock exchange. With regard to the considered criteria, 100 companies among 9 industries were selected as sample based on two digit ISIC codes. Findings of research indicate that the companies which enjoy the pricing power at product market less likely manage their earnings. Another finding indicates that earnings management increases by increasing competition in industry. Hence, the investors who intend to invest in competition industry should pay more attention to earnings management.