This study is to inquire into the effect of collage art therapy for self-esteem and career maturity of a school-maladjusted adolescent. A participant was a school-maladjusted adolescent of B high school in A city, and the research was conducted as a single case study. Collage art therapy was practiced 50 minutes per session, semiweekly, 9 sessions in total. In order to examine of effectiveness of the therapy, pre- and post-test of self-esteem and career maturity were conducted. Then changes of the student’s behavior and art practice were analysed qualitatively after each session. The results are following: First, the collage art therapy was effective for improving self-esteem of school maladjusted adolescent. Second, the collage art therapy was effective to enhance career maturity of schoolmaladjusted adolescent. Third, self-esteem and career maturity were improved as sessions continued. Forth, the student’s change in collage art practice could indicate the student’s progress in building positive self-image and future image. Similarly overall format of the drawings became stable. Therefore, collage art therapy was affected positively on the improvement of self-esteem and career maturity for school maladapted adolescent. In conclusion, collage art therapy was helpful to improve of(x) self-esteem and career maturity of school-maladapted adolescent by the effective interactions between self understanding and achievement of art.