This study empirically analyzes the economic validity of rape farmers. The analysis of economic evaluation is based on the benefit-cost analysis. Previous studies have undoubtedly expanded our understanding of the importance of substitution effects on a rapeseed for bio-fuels. However, earlier studies have mostly dealt with the concept of biodiesel"s economics analysis, but this paper"s attentions have been paid to the economic analysis of farm. The aim of this paper is suggesting the most appropriate policy brings about why farmhouses should cultivate the rape. To answer this question, this paper adopts a scenario analysis and the B/C ratio is used.