The purpose of this study is to find the effect of transformational․transactional leadership on organizational citizenship behavior - focusing the mediating variables of trust -. To accomplish this research objective, this study collected data from 679 employees in 50 luxury hotels in Korea and surveyed with questionnaire method. The result of this empirical study is summarized as followings. First, transformational leadership has a positive effect on organizational citizenship behavior, but transactional leadership has no effect on organizational citizenship behavior. Second, transformational leadership is more closely related with organizational citizenship behavior than transactional leadership. Third, transformational leadership has more effect on organizational citizenship behavior with the intermediary variable of trust, but transactional leadership has no effect on the organizational citizenship behavior. The results of this study indicate that, as a motivation for the organizational citizenship behavior, development of transformational leadership and trust building between a leader and members of organization are very critical.