A public open space is an urban facility which has significant influence on a community's formation. This study has two purposes. 1. To clarify the significance of community formation via resident's management of public open spaces. 2. To clarify the support of local government and activity of local residents for the improvement of a community. The study area is greenway Imaigawa Ikoi-no Mizube in Yokohama city. This study consists of the questionnaire investigation of the members of the Imaigawa Ikoi-no Mizube care organization which is a voluntary organization of local residents, the questionnaire investigation of the other residents of Imai-cho, and the fieldwork at the greenway. The results of these investigations were viewed according to five factors of community formation and two indexes of community value. Through these examinations, we came to two conclusions. 1. Management by the local residents contributes to a community's formation by synthesizing the image of future, deepening the attachment to the area, and deepening and widening communication. 2. For the improvement of a community, local government support and public relations is essential to not only lead the residents to autonomous activity, but also to join the care organization.
