The purpose of this study was to verify the improvement of children s attachment and peer relationship skills by conducting mother-child group art therapy. The subjects in this study were 13 teams of five-year-old infants and their mothers who living in K City in Gyeonggi-do. The mothers reported that their children had difficulties with attachment and peer relationships. From June 29, 2019, to August 6, 2019, the Mo-A group art therapy program was conducted twice a weekly for a total of 12 sessions. The research tools consisted of Attachment Q-set(Version 3, AQSⅢ), the Penn Interactive Peer Play Scale, and the Bird s Nest Drawing Assessment, and the collected data were analyzed using the SPSS 23.0. The Mann-Whitney U test was performed to ensure the homogeneity of the experimental and control groups, and the Wilcoxon signed-rank test was used to verify the effectiveness. This study was statistically significant at α=.05 significance level. As the mother played the role of a safety base, ta positive change could be observed in the infants’ attachment response, and the decrease in the infant s negative peer relationship behavior showed a statistically significant difference, confirming ta positive effect on the peer relationship. Based on these results, the implications and limitations of this study are discussed.