The purpose of this study was to investigate the effects of an interpersonal relationship improvement program on self-esteem, interpersonal orientation, and ego-resilience on Korean adolescents. In this randomized controlled trial (RCT), 62 eligible participants were randomly assigned to either group A (intervention, n=30) or group B (usual care, n=32). Self-esteem, interpersonal orientation, and egoresilience were measured at the baseline, and a three-week follow-up was conducted. The t-test was then used to determine the effect of intervention. The mean self-esteem (p=0.002), interpersonal orientation (p=0.000), and ego-resilience (p=0.000) significantly increased after intervention. Thus, the results of this study suggested that the interpersonal relationship improvement program could be utilized as an effective means to improve mental and social health of adolescents.