"This study purports to see if a mandala-based group art therapy can help institutional children improve their social competence by learning the skills of cooperation, self-expression, self-control, and sympathy. the study subjects are ten children residing in J Child Care Institute of D city, who have suffered from the lack of social skills. they were given the group art therapy program consisting of a total of 8 sessions, twice a week with each lasting 120 minutes. Matson's Measure of Child Social Skills (versions for teacher and for Child) was taken for posttest as well as pretest. SPSS WIN 12.0 was used for data analysis, adopting the methods of average and standard deviation between pretest and posttest results, and dependent sample t-test. the results are as follows. First, negative or inappropriate behavior has been reduced while positive or appropriate behavior increased. Second, social competence or skills of cooperation, self-expression, self-control, and sympathy have been improved. It can be claimed therefore that a mandala-based group art therapy is positively effective in improving the social competence of institutional children. Key Words : Mandala, Facilities Children, Social Skills"