Abstract
We have developed, in this paper, a method for evaluating effective potential for local composite fields based on loop expansion by first renormalizing the generating functional of connected Green's functions and then making the Legendre transformation. A consistency condition reflecting the fact that no condensate effect occurs at tree level is proposed, which plays an important role in this method. The method is illustrated through the Gross-Neveu model. This method can be applied to a wider class of models than can the auxiliary field method.