The toxics regulatory body provides a benefit/cost ratio as a justification criterion while implementing regulations that induce the industry to reduce emissions voluntarily. Furthermore, since, the body wants to reflect not only the efficiency standard but also the policy standard in the evaluation of feasibility, it calculates the ratio by adjusting the importance weights. The problem is that respondents answer ambiguously. It should be removed for the reasonable evaluation. This study introduced a fuzzy-AHP methodology for this, and applied it to the voluntary emission reduction plan program in Korea.