This study was conducted to investigate whether group play therapy program is effective in improving social skills of children with intellectual disabilities. First, the effect of the group play therapy program on the changes in the scores of the social skills scale of children with intellectual disabilities is investigated. Second, find out the effects of group play therapy program on pro-social behavior of children with intellectual disabilities. The subjects of the study were 7 children that were diagnosed with intellectual disabilities aged 10-12 using the A center located in D city. The group play therapy program was conducted twice a week for a total of 12 sessions for 6 weeks. As a result of the study, the social skill scale of children with intellectual disabilities in the ex�perimental group was increased in the post-test compared to the pre-test. Second, as the session progressed, the incidence of pro-social behaviors of children with intellectual disabilities in the experimental group steadily increased and showed social improvement.