The major purposes of this thesis are to investigate the key roles of team leaders and to analyze the desirable team climate in the R\&D project teams. Team leader's 5 key roles(planner, team builder, expert, gatekeeper, and champion) and innovative team climate(autonomy, innovativeness, cohesiveness, tension) are constructed from the theorectical leader's functions, qualifications, key roles in innovation process and empirically tested from 86 R\&D project teams of 6 Research institutes. Both leader's key roles and innovative team climate determine the team performance(superior team vs. ordinary team, team efficacy, job satisfaction, organization commitment), and especially key roles are more related to team performance when leader's team tenure is much longer and task uncertainty is much higher. This study also demonstrated that key roles are closely related to transformational leadership style. These results indicate that team leader's role harmonized with his transformational leadership behavior is very important determinant of team performance. The cohesiveness dimension of innovative team climate is conducive to the team performance, and innovative team climate is higher when leader deploys his 5 key roles fluently. This imply that leader's encouragement of innovative team climate is more helpful management skill during project leading to completion.