Although the study of OCB has increased greatly in recent years, a little works have focused on the relationship between individual difference factors and extrarole behavior, and the moderating effects of sex on the relationship between two factors.The first purpose of this paper is to examine the relationships between 2 individual difference factors(collectivism, needs for achievement) and organizational citizenship behavior(OCB), and the second purpose is to review the moderating effects of sex on the relationships. To assess the moderating effects, the hierarchical regression procedures outlined by Cohen & Cohen(1983) and Baron & Kenny(1986) were applied.According to the empirical analysis based on the data from 698 teachers out of 50 primary and secondary schools in Wonju province, it is found that collectivism and needs for achievement have impacts on OCB. Specially needs for achievement has more impacts on OCB than collectivism. Also it is found that needs for achievement has more affirmative impacts on courtesy in male teachers group than in female group. And it is resulted that collectivism has significant impact on civic virtue in male group, but not in female group.