This study purports to find the effects of sandplay therapy for the changes in self expression and social participation, which are the main problems occurring to a child with depressive tendencies. The subject of this study, a 5-year-old boy, was given 50 minutes a week session of sandplay therapy for a course of twenty weeks. In the course of the sandplay therapy, concerning changes in self expressions, there was very little self-expression shown in the early stages, yet as the therapy progressed the subject started attempting self-expression, and of these non-linguistic expressions was more dominant than linguistic expressions. Later into the course, linguistic self-expression were shown in increasing amounts, and in its final stages active linguistic expressions and actions manifested. Concerning social participation, the subject had little movement and hardly used the apparatus in the early stages, yet in the middle stages he became interested in the apparatus needed for his playing and indeed attempted to use them, and also formed a relationship with the therapist. As the therapy progressed into the latter stages it was shown that he actively used the apparatus to express his inner self. With sandplay therapy, the child with the depressive tendencies showed positive changes in self-expression and social participation through therapeutic episodes and in everyday life. This study confirms that sand play therapy is effective in changing self-expression and social participation in a child showing depressive tendencies, and it concludes that the child deviates from depressive tendencies through sandplay therapy.