The purpose of this study is to improve the self-efficacy of the low-income family children through the group sand tray play. The subjects of the study are 3 children, who wanted to participate in the group sand tray play with the children whose total score of self-efficacy criterion was under 70, among the low-income family who used the afterschool classroom in a child care center in area K, D City. The study questions are the effect of group sand tray play on the self-efficacy and self-efficacy behavior of low-income family children. The group sand tray play was conducted twice a week, 50 minutes per 1 session, total 10 sessions in the child care center learning room in area K. The results were as follows: First, the group sand tray play improved the self-efficacy of the low-income family children. Second, the group sand tray play had a positive effect on self-efficacy behavior of the low-income family children.