Purpose: The purpose of this study is to analyze factors affecting suicidal ideation of athletes in middle and high school. Methods: The data in this study came from the survey which conducted to 500 students of physical education high school athletes and elite athletes in general school from the beginning of December 2009 to the end of January 2010 in Seoul and Kyunggi. Finally 436 cases was used. The dependant variable is suicidal ideation in this study. And the independent variables are socio-demographic factors, exercise-related factors, school and family environments, stress and depression factor. The analysis method is logistic regression analysis. Finally 436 cases was used. Results: First, the rate of suicidal ideation of athletes in middle and high school was 28.9%. Second, there were significant differences between stress and sex, grades, athletic career, kind of sport, sport skill level, the average exercise time per day, family circumstances, life satisfaction, future expectations. Third, there were significant differences between depression and sex, academic achievements, the average exercise time per day, family circumstances, life satisfaction, future expectations. Fourth, there were significant differences between suicidal ideation and sport skill level, academic achievements, the average exercise time per day, family circumstances, life satisfaction, future expectations. Fifth, the higher level of stress and degree of depression, the more increased the risk of suicidal ideation. Conclusions: Considering the close relationship between suicidal ideation and suicidal attempt, to reduce the suicidal ideation of athletes in middle and high school it is necessary to adjust exercising time properly and to promote life satisfaction. Also to overcome depression and stress support system should be established and to promote self-efficacy cognition strength program should be introduced in the school. So athletes in middle and high school should have confidence and self-confidence on the future.