Contingent valuation method (CVM) has lately attracted an attention for method estimating the environment value because of its sound and theoretical basis and its flexibility. Now in Europe and America, there have many applications of the CVM to estimate environment damage in a framework of cost benefit analysis. But it is pointed out that the CVM has many structural biases because of survey design, evaluators consciousness and the like. This study is designed to investigate the factor estimating the value of the environment improvement project.
