The purpose of this study was to investigate the effectiveness of sandtray therapy to improve social skills of school maladjusted children. The subjects of this study were low-income family children attending elementary school in J city. They showed maladjustment of school life due to difficulties in school life and peer relations due to lack of social skills, and they were counseled by homeroom teacher and parents. The period of this counseling room was from 30 September 2016 to 23 November 2017, and sandtray therapy was performed once a week for 50 minutes for each session for a total of 30 sessions. First, what is the post hoc transition in order to improve the social skills of school maladjusted children? Second, what is the pre-event change in the social skills of school maladjusted children? Third, what is the pre - and post-change of the case of sandtray therapy to improve social skills of school maladjusted children? The results of this study are as follows: First: In the stage of development and adaptation in the sand box, self-realization is achieved with totality. Second, the HTP test shows differences in communication, sociality and autonomy compared to the pre-test. Third, Social skills scales were significantly different from pre-test. In other words, sandbox therapy is a technique using sandtray therapy to help the problem of maladjustment of school maladjusted children. Through this, it can be said that it is very useful as a way of expressing the inner world of the child, integrating unconsciousness and consciousness, strengthening self, and healing problematic behavior.