In this study, we examined the factors which determine organizational citizenship behavior (OCB), voluntary and extra-role behaviors by employees within organizations. Japanese employees (N=187) completed questions about OCB, justice in organizations, leadership styles of their superiors, job satisfaction, organizational commitment, and organizational support. Multiple regression analyses revealed that: a) the higher procedural justice was evaluated, the more Japanese employees were likely to display OCB, b) the effect of distributive justice on OCB was weaker than procedural justice and interactive justice, c) as higher-level Japanese employees had more job satisfaction or organizational commitment, they were more likely to display OCB. In addition, Japanese employees who evaluated organizational support more highly were more likely to display OCB. Covariance structure analysis indicated that the evaluations of interactive justice and supportive leadership by superiors indirectly enhanced OCB. Based on the results of analyses, we discussed OCB in Japanese corporations.