This study aimed to understand whether the group sand tray play program improved the social competence of single-parent children. To understand the effect of the group sand tray play on the social competence of the single-parent children, self-reported social competence tests were performed before and after the program and the behavioral changes to social competence was analyzed during every session. The study results are as follow. First, the group sand tray play program improved the social competence of three single-parent children upon self-reported social competence test. Second, they showed the positⅣe behavioral changes of social competence during the program. Therefore, we found that the group sand tray play program was effectⅣe to improve the social competence of single-parent children although this study had some limitation hardly generalizing due to the small scale case reports.