The purpose of this study was to investigate whether group art therapy using a three-dimensional modeling activity, positively affects children’s creativity and sense of happiness. The subjects of the study were 24 children in the 6-year-old children s play school in D-gu, Seoul, and a total of 24 infants who received parental consent to participate. The study period spanned from September 3, 2019 to December 31, 2019, and a total of 18 sessions of the program were conducted for the experimental group once a week for 90 minutes. As research tools, the infant comprehensive creativity test and infant happiness scale were used. In order to increase the reliability of each item in the creativity test, the ICC value was calculated, and the reliability was measured among a total of four scorers, including this researcher to analyze the change. As a result, first, group art therapy with three-dimensional modeling showed a statistically significant effect in the change of four creativity sub-factors. Second, the three-dimensional modeling activity group art therapy showed a statistically significant effect in 6 of 9 happiness sub-factors. Third, the experience of independently manipulating the use of various art media in the activity content analysis for each stage of the program helped children creatively express themselves and the feelings of immersion and satisfaction expressed through such that creative expression helped children improve their sense of happiness. Based on these results, the implications and limitations of this study are discussed.