Purpose : The purpose of this study was to investigate the influencing factors of subjective well-being, which ROK military cadets were feeling. The authors assumed that the cadets' subjective well-being would be increase when they met their psychological needs consisting of autonomy, competence and relatedness with social support from their peers, family and the faculty. Method : Samples included 1,044 female and male cadets, ranging from freshmen to senior, from three different military academies including the AFNA. The participants responded to 81 item questionnaires measuring their perceived social support, basic psychological needs satisfaction and subjective well-being. As a way to see the causal relationship among the three variables above, the Structural Equation Modeling Techniques were used. Results : As expected, causal relationships were found between the social support, basic psychological needs satisfaction and subjective well-being with the Structural Equation Model. Among others, autonomy was found to be the factor which significantly influenced on all the three elements of the cadets' subjective well-being, life satisfaction, positive and negative affect. Conclusion : In order to improve the level of their cadets' subjective well-being, ROK military academies should make an effort to develop a psycho-social supporting system.