The main purpose of this case research is to lower the level of anxiety of a mother and her daughter, who have shown high level of anxiety simultaneously, and to induce ego growth and psychological stability for both of them. Patients were a 5 years old girl and her mother. The problem with the girl was alleged tension, separation anxiety, low level of self-assertiveness, and a tendency of showing adult-like nurturing attitude to attract attention from others. The problem with her mother was that she was having tensions toward her family members and other people and she was anxious about her children. Separate sandplay therapies were done for the child and her mother. For the child, both preliminary psychology test and post-therapy test were done by HTP. A Sentence Completion Test(SCT) was done for her mother. In total there were 29 sandplay therapy sessions for the child and 16 therapy sessions for her mother. Changes in level of anxiety in both of them and improvement in daily life and relating with peers for the child were measured during and after the therapy. The results are as follows: First, as the child’s anxiety lessened, she did not show separation anxiety when going to nursery. Second, the child showed improvement in self-assertiveness and she was able to build positive relationship with peers. Third, her mother regained psychological stability and her level of tension and anxiety about human relationship and nurturing have lessened substantially.