The purpose of this study was to determine whether a situation moderates the effects on group members of leadership and prototypicality. Prototypicality is a concept defined as recognition of the standpoint between individuals who reflect the meta contrast ratio of an ingroup and outgroup, and this prototypicality relates to an evaluation of the leader's effectiveness by the group members (e.g., Hains et al, 1997). In this article, we examined whether a leaders' prototypicality strongly influences group activity. In study 1, we conducted an investigation on 205 members of 18 groups of university students. The results showed that prototypicality increased group morale when the activity was a competition with an outgroup. In study 2, group members' judgment relative to the instructions of the leader was examined using the scenario assumption method. Results revealed that only in a situation of conflict with an outgroup did the leaders' prototypicality become the group members' judgment standard. The two studies suggest that a leader's prototypicality influences group members only when there is clear conflict with an outgroup.