This study aimed to investigate the internal world of a female middle school student who complained of various physical symptoms every new semester, washed her hands repeatedly, and had difficulties in peer relationships through sandplay therapy. Thirty-nine sessions were held. In the initial phase of therapy (1st session, separation from mother image), the client expressed instincts that did not function naturally, and began the internal journey to separate from the mother image and to find femininity. In the intermediate phase of therapy (2nd-31st sessions, descent to unconsciousness, finding femininity and identity), she descended to the dwarf village in the viewpoint of analytical psychology due to the intrusion of mother image to move from the infantile world to the mature life. The client found her own rhythm by meeting with herself through the works of unconsciousness. The wounded instincts were cared for, and healing started. The client expressed negative masculinity, femininity, identity, shadow, possibility of integration, and unity of the opposites, and experienced the journey to make instincts function well with realizing her own talents and characteristics. In the final phase of therapy (32nd-39th sessions, reconciliation, communication), as the consciousness was expanded by the communication of unconsciousness and consciousness, the separation from mother image occurred, and anxiety and pressure disappeared. The therapy was completed by expressing that there was a change of masculinity as well as having the insight of courage to challenge mistakes or failures. In real life, somatization symptoms disappeared, repetitive hand washing behavior almost disappeared and relationships with friends changed. The study showed that sandplay therapy was effective for the client because various somatization symptoms and hand washing were alleviated, and peer relationships were changed.