An investigation of the relationship between sentimental decision-making of investors and investment efficiency of listed companies in Tehran Stock Exchange and the role of corporate governance in this regard, is the main purpose of this research. To achieve the purpose, the data of 138 companies as sample by selecting a systematic delete method (screening) during the period 2008 to 2015 were used. The impact of variable related to sentimental decisions investors (Equity Market Sentiment Indicator) on investment efficiency (based on Richardson, 2006) through multivariable liner  regression models to estimated generalized least squares method (EGLS) with fixed effects were investigated. Hasasyeganh-salimi model (2011) for assessing the corporate governance consists of 93 indicators were used. The role of corporate governance on the mentioned relationship was examined by another regression model.The results showed that sentimental decisions investors have a significant negative effect on investment efficiency. In other world, sentimental decisions investors has an adverse impact on corporate investment decisions and investment efficiency. But corporate governance, while having significant positive effect on investment efficiency, the ability to mitigate the adverse impact of sentimental decisions investors on corporate investment efficiency.