The previous study points out a significant relation between state of ego and psychological skills such as social skills and psychological competitive abilities. Other studies clarify that the psychological support intending to improve state of ego can be effective for contributing to the solution of psychological issues. This study examined two issues by a case. The one was to verify the significant relation between state of ego and psychological skills. Another one was to examine the influence that psychological support based on ego function analysis gives to the athlete’s personality development, psychological competitive ability and social skills. The case was executed for a female tennis player and consisted of 7 sessions about 1 hour per month. The results indicate that the study discussing about a significant relation between state of ego and psychological skills was almost supported. Then, the case showed that the psychological support improved the way to catch interpersonal relationship and brought on a change of attitude toward competition in tennis. In conclusion, the approach in the present study showed a new possible application in the development of psychological support based on personality development.