The purpose of this study was to test effects of traditional play based physical activity program on social competence. To obtain this purpose, the following research hypotheses were established. First, experimental group will show higher level of social activity than control group. Second, experimental group will show higher level of stability than control group. Third, experimental group will show higher level of cooperation than control group. Fourth, experimental group will show higher level of hypersensitiveness than control group. Forty eight four year children participated in this study. Iowa Social Competency Scale(Preschool Form) was used to measure children’s social competence. Collected data were analyzed using t-test and analysis of covariance. The results of this study showed that program was effective in improving children’s socal competence. These results were discussed in relation to previous study. Finally research questions for future study were suggested with comment on limitations of this study.