To achieve optimal risk-taking in financial institutions, effective corporate governance mechanism, as a risk management tool, perform better than the legal requirements. So, in this research, we investigate the impact of corporate governance on capital adequacy and deposit cost coverage as risk indicators. In this regard, we use Iranian Banks and financial institutions data for the period of 2011-2015. We examine this impact with using Generalized Momentums Method (GMM) estimation method. The results show effective corporate governance enhances capital adequacy and deposit cost coverage ratios and therefore decrease the financial institutions' risk. Also, ownership concentration and risk are associated with nonlinearly. The findings support corporate governance theory that it says the owner's ability to influence bank risk is depended on ownership structure.