The purposes of this study were to verify the validity of the psychological stress model in high school athletes, and to investigate the relationship between each variable of the psychological stress process. The subjects were 449 first and second year high school athletes (245 males and 204 females). They were required to complete a questionnaire that consisted of a stressor scale for his/her performance, a cognitive appraisal scale (2 subscales: influence of stressors, and controllability), a stress-coping scale for high school athletes (5 subscales: problem solving, avoidance, catharsis, distractive recreation, and positive thought), a stress response scale for high school athletes (5 subscales: depressive-anxious feeling, irritated-angry feeling, restlessness, helplessness, and withdrawal), and a motivated participation scale for athletic club activity. First, the validity and reliability of the cognitive appraisal scale and motivated participation scale in athletic club activity were verified through factor analysis. Second, hierarchical multiple regression analyses were conducted assuming the following process "stressor → cognitive appraisal → stress-coping → stress response". The results verified the validity of the psychological stress model in high school athletes, and found that there were two patterns of psychological stress process. One was "influence of stressors → emotion-focused coping → increasing of stress response" and the other was "controllability → problem-focused coping → decreasing of stress response". Finally, the psychological stress process, from stressor to motivated participation in athletic club activity, was analyzed as an index of athlete adaptation. As a consequence, it was shown that the relationship between cognitive appraisal and stress-coping had a positive effect on motivation in athletic club activity, and it was clarified that actual athlete adaptation followed an almost linear course through the steps of the psychological stress model.