This study has analyzed overseas projects of building rural communities using vacant houses. It is aimed at identifying the roles of NPO in the community-building projects and providing implications applicable to Korea. In recent years, there has been a spike in the number of vacant houses in rural areas. It is due to rapid urbanization and uneven distribution of the population across the country. Those are the reasons that prompted community-building projects. To solve the vacant house issue, there has been rising interest in building communities through vacant houses as rural resources and effectively integrating them as useful resources. However, the roles of key entity that pursues community-building projects using vacant houses have not been discussed sufficiently. Thus, this study deals with the 'Vacant House Recreation Project of NPO Corporation in Onomichi' in Hiroshima, Japan. Through the case study, the following are introduced as NPO's roles in community-building projects using vacant houses. First, pursuing promotion and attracting attention by making the utilization of vacant houses sensational; system improvement; offering information. Second, enhancing the perception of local residents by offering local services using vacant houses; offering community-building items. Third, forming a place of public discussion to solve conflicts during community-building projects using vacant houses; offering alternatives to building communities. Above all, such roles have led to the key status of NPO during its community-building projects using vacant houses. It offers the following implication for Korea: Future vacant house-related policies for rural revitalization should be done from community-building standpoint and include establishing the roles of NPO.