Disclosed is an anticancer composition, comprising an inhibitor against WIG1 and/or YPEL5 or against a protein encoded by the gene. A composition for screening an anticancer agent comprising a nucleic acid having a sequence complementary to an mRNA of WIG1 and/or YPEL5, or an antibody to a protein encoded by the gene is also provided. Also, a method is provided for screening an anticancer agent, which comprises: (A) quantitatively analyzing expression of WIG1 and/or YPEL5 at an mRNA or protein level in a tumor cell which is not treated with a candidate for an anticancer agent; (B) quantitatively analyzing expression of the gene at an mRNA or protein level in a tumor cell after treatment of the candidate for an anticancer agent; and (C) selecting the candidate if the expression level of the gene is increased in step (B), compared to step (A).