This study focuses on the roles of two situational moderating variables based on the leadership dynamics of dyadic relationships between leaders and members. In particular, it tested whether the duration of the leader-member dyadic relationship and subordinates' growth need strength, as situational variables, have moderating effects on the relationship between individually-oriented leader behavior and leadership effectiveness, using a sample of general employees at securities firms. The results of this study empirically demonstrated that the duration of the dyadic relationship has a significant moderating effect on the relationship between two types of leader behaviors and performance, and that growth need strength has a significant moderating effect on the relationship between initiating structure leader behavior and job satisfaction. Therefore, these results provide opportunities to discover various methods for leadership flexibility that can more effectively manage leadership dynamics over time and employees' diverse needs for leadership according to the situation—that is, enabling leaders to act in a situationally contingent manner when facing different subordinates and circumstances.