This study sought to learn the effects of positive psychology-based group art therapy on the self-efficacy and subjective happiness of art therapy major students. Twenty students voluntarily expressed their willingness to participate in the study among art therapy majors at C University, Gyeonggi-do. The study subjects were randomly assigned to an experimental group and a control group, each of which had 10 students. The experimental group participated in weekly 90-minute group art therapy program sessions, from May 2, 2019 to May 30, 2019, for a total of six sessions. The study untilzed self-efficacy and the subjective happiness scale, and for qualitative analysis, the study used the self-efficacy, subjective happiness change, and self-reflective writing changes. The results of this study are as follows. First, positive psychology-based group art therapy had a significant effect on the self-efficacy of art therapy major students. Second, positive psychology-based group art therapy had a significant effect on the subjective happiness of art therapy major students. Third, positive psychology-based group art therapy showed positive change in the self-efficacy and subjective happiness of art therapy major students. Therefore, positive psychology-based group art therapy was found to be effective and positive in improving self-efficacy and subjective happiness of students majoring in art therapy.