This paper aims to investigate the effectiveness and problems od social group representative system as a participation method in community development by partnership through the case study. (1) It is possible to make use of their characteristics in planning process with including social groups that act in related area. The communication function of group is effective for opening the process with including social groups that act in related area. The communication functon of group is effective for opening the information of planning process to public. (2) In order to promote the planning smoothly, enlightenment of representative participants from each group is necessary for getting the agreement of cooperation preliminary to planning. (3) It is necessary to bridge the difference of cognition between each participant through the cooperative process for improving the acceptable level of plan.