The purpose of this study was to investigate the process of nondirective play therapy using observational instrumental based on naturally expressed children's play during therapy sessions. Twelve sessions were carried out for a 43 months' age girl and her mother who had difficult experienced in parent child relationship. The results are as follow: First, child's intelligence, emotion, and social intelligence has been change as time goes by. Second, play themes were Relationship, Nurturing, and Protection. Third, play profiles were suggested based on play behaviors during therapy sessions. These results can apply to understand children's play behaviors and the meaning.