A strong board can play a key role in increasing firm performance and value and lead to value creation. as a result, properly performing duties and responsibilities can be effective on attracting investment opportunities. on the other hand, under the ethical risk model, managers who are not adequately monitored over their performance may benefit from the information advantage that may be more or more efficient than the optimum level; therefore information asymmetry could affect the effectiveness of firms' investment. the purpose of this study is to investigate the relationship between board characteristics and investment efficiency in tehran stock exchange and also the effect of information asymmetry on this relationship. This study investigated the financial information of 132 firms accepted in tehran stock exchange during the years 1392-1400. to test the research hypotheses, regression model was used with panel data method and fixed effects. Analysis of the findings indicates that the characteristics of the board have a direct and significant relationship with investment efficiency and asymmetry of information asymmetry moderates the relationship between board characteristics and investment efficiency. The results indicate that the board affects the company's investment efficiency through monitoring and maintaining relationships with shareholders, and the board with improved information environment can help reduce the information asymmetry between the management and the shareholders that lead to optimal investment in the company.