This study investigated the effect of group art therapy using mandalas on the brain quotient of elementary school students. The participants of the study were 24 elementary school students in the grades 4 through 6 in the city B. They were divided into the experimental group of 12 and control group of 12. The therapy program was given three times a week, fourteen sessions in all, each session 90 minutes long. Each participant of both groups individually received a brain wave test before and after the program, and later as a follow up. The brain wave measurement was performed based on brain quotient using a neuro-feedback brain wave measuring machine developed by Korea institute of Jungshin Science. Data collected from the experimental and control group were computed on SPSS WIN V.17.0. Repeated measures analysis of variance was computed for a statistical analysis. The brain wave measuring equipment measured brain quotient and its subcategories: Self-regulation quotient, Basic rhythm quotient, Attention quotient, Activation quotient, Emotional quotient, Stress quotient, and Correlation quotient. The measurement showed that the group art therapy using mandalas produced significant difference in the brain quotient. In addition, effects were found in the subcategories such as Self-regulation quotient, Attention quotient(the left and right brain), Activation quotient(the right brain), Emotional quotient. The findings of this study suggest that the group art therapy using mandalas was effective in causing change to the brain quotient of elementary school students.