It is evident that a financial feasibility study based on the economic analysis has been theoretically and practically accepted in the aspect of its adequacy. However, it is not easy to apply in the practical business affairs since there exist some difficulties on the economic analysis and the interpretation of the result because of the difficulty of the estimation of the discount rate. This study aims to suggest a method of the financial feasibility study based on the economic analysis. The results of this study are as follows. First, this study can increase the reliance and adequacy of the economic analysis result by suggesting a method of estimating the discount rate by means of the proxy ${eta}$ method in the practical way. Second, this study can provide the overall frame of the financial feasibility study based on the economic analysis method (namely, Net Present Value Method internal rate of return, profit index method and payback period method)which use discount rate and cash flow. Third, this study can suggest an practical analysis skill required in each step of the financial feasibility study.