This is a case study of family therapy in which a mother has asked for consulting for child who are having difficulty in forming peer relationships. The family who participated in this study consisted of five family members consisting of two parents, two daughters and one son. The consultation was carried out 16 times. This study analyzed the categories formed on the basis of the notes recorded during consultation and the 16 counseling sessions using the matrix method proposed by Miles and Huberman(1994). Analysis revealed that the factors affecting the difficulty of forming peer relationships were the empirical characteristics found from the family of origin transmitted to the family and the dysfunctional communication method between the couple. Through these treatments, the child gradually became able to form positive relationships with their peers, and there occurred changes in family members' personal and family relationships.