Purpose: The purpose of this study was to investigate the effects of a positive psychology-based mental health promotion program for high school students. Methods: This study used a randomized control group pretest-posttest design. A total of 47 high school students participated from two high schools in Gyeonggi Province. They were randomly assigned to an experimental group (n=24), which participated in the 8-session program, or to a control group (n=23). Psychological well-being, depression, and self-esteem were measured. Results: A significant difference in psychological well-being was observed between the two groups after the program. However, there were no significant between-group differences in depression or self-esteem. Conclusion: The positive psychology-based mental program was effective at increasing psychological well-being in adolescents, especially high school students. This study suggests that a school curriculum could incorporate positive psychology-based mental programs for high school students to promote their mental health.