This study investigated the effects of art therapy on improving the interpersonal relationships and study attitudes of adolescents with overt narcissism. The study participant, a 19 year-old male adolescent living in an urban setting, received a 29 session art therapy program from June, 2011 until December, 2011. The therapy ran once a week, each session 100 minutes long. The participant was administered an overt narcissism scale before and after the therapy, and at a follow-up evaluation. In addition, the participant answered 5 question items of interpersonal relationship and 5 question items of study attitude before and after art therapy. The answers to 5 item questions of interpersonal relationship and 5 item questions of study attitude were compared before and after art therapy to detect any cognitive change. The participant and his parents analyzed and scored the behavior and sentiment of each item before and after art therapy, and at a follow-up evaluation. Firstly, the study found that art therapy improved the interpersonal relationship of the participant. As the overt narcissism reduced, positive change was found in the participant's sentiment and behavior in his interpersonal relationship. Secondly, the study found that art therapy improved the study attitudes of the participant. As the dysfunctional feelings of narcissism reduced, the participant became active in changing his behavior. These findings suggest that art therapy was effective in improving the interpersonal relationship and study attitudes of the participant.