The purpose of this study was to investigate the Relationships of the Stage of Exercise Behavior Change and Physical Activity on Ego-resiliency, Interpersonal Anxiety and Prosocial Behavior in Children. A total of 288 children participated in this study and physical activity was measured by pedometer. Also, physical activity were divided into 3 groups(Low group, Mod group, High group). In order to verify psychological factors, Stage of Exercise Behavior Change Inventory, Ego-resiliency Inventory, Interpersonal Anxiety Inventory and Prosocial Behavior Inventory were used. The statistical techniques used for the analysis by using SPSS WIN 18.0 version. The implications of this study are as follows; According to the differences of Ego-resiliency, Interpersonal Anxiety and Prosocial Behavior on physical activity, Physically active children showed significantly low in Interpersonal Anxiety and significantly high in Ego-resiliency and Prosocial Behavior. According to the differences of Ego-resiliency, Interpersonal Anxiety and Prosocial Behavior on the Stage of Exercise Behavior Change, higher the Stage of Exercise Behavior Change, Interpersonal Anxiety was lower. Whereas, higher the Stage of Exercise Behavior Change, Ego-resiliency and Prosocial Behavior was generally higher. Physical Activity and the Stage of Exercise Behavior Change were negative effect on the nterpersonal Anxiety and also these were partially positive effect on the sub-factors in the Ego-resiliency and Prosocial Behavior. These results suggest that Physical Activity and the Stage of Exercise Behavior Change may be a mediator for the child's psychological factors.