The purpose of this study was to investigate the effect of self-expression-focused group play therapy on the peer relationship of children with emotional withdrawal. First, we investigated the change of peer relations of children with emotional withdrawal. Second, the self-expression-focused group play therapy investigated the change of the peer relationship of the child with emotional withdrawal in reported by the teacher. Third, the self-expression- focused group play therapy is to investigated the change of peer relations skill behaviors of children with emotional withdrawal. The study subjects were four children who were referred to U-City G Children’s Center for atrophy and over 70T in the atrophic area of K-CBCL. In order to investigate the changes of peer relations, children’s peer relationship test and teacher peer relationship test were compared to compare pre-post scores. Behavioral frequency was measured according to technical behavior observation scale (peer-matching behavior, self-expression behavior). The results of this study are as follows. First, self-expression-focused group play therapy improved in peer relationship of children with emotional withdrawal. Second, self-expression-focused group play therapy improved the peer relationship of the child with emotional withdrawal reported by the teacher. Third, self-expression-focused group play therapy improved children’s peer relationship skills (peer-to-peer behavior, self-expressive behavior) behaviors with emotional withdrawal.