Due to rapid urbanization, farmland is declining in suburban areas. The environment of agriculture in suburban area is severe as reflected in changes in rural societies, encroachment of farmland and invasion by urban land use such as residential place, commercial areas, increasing land prices and the problem of inheritance tax. In order to deal with such circumstances, preservation of farmland is essential, and various policies and activities regarding preservation of farmland are implemented. Public ownership of farmland is one of these methods. Its purpose is that public organizations acquire the private farmland which cannot be managed by its legal owners, and manage it in such a way that its productive potential is preserved. The importance of this method is increasing in suburban areas. Public farmland is managed by its continuous use as farmland, but the sustainable management system of public farmland in suburban areas is not clear enough. Sustainable management system is defined as continuous utilization of public farmland by people. Therefore, this research aims to clarify the working of the sustainable system of public farmland in suburban areas. This research is based on the systems theory for management of agriculture of Bryant and Johnston (1992) , which looks at the elements of planning, land, labor, capital and management, as the key elements of the system. In order to apply it to public farmland, however, capital and management (which are conducted by the administrative body and as a consequence remain stable) can be ignored and only planning, land and labor variables are considered. Taking into consideration the characteristics of public farmland, the following relationships and activities are considered in place of planning, land and labor respectively: the relationship between the managing entity, which is a general term for the land owner entity, the management entity and the user entity, and the type of activity (planning), the relationship between the public farmland and the function of farmland exerted by the type of activity (land), and the leisure and educational activities (labor). In addition, based on the private interest and the public interest in the main functions of farmland in urban fringes conceptualized by Bryant and Johnston, the 4 functions of production, protection, play and education are considered in the case of public farmland, and the framework of this research is formulated. Minum a rice fields in Saitama prefecture is focus of the present research. Minuma rice fields suffered severe damage by typhoon No.12 (Kanogawa typhoon) in 1958. All the areas of Minuma rice fields were flooded and most part of the urban area of Kawaguchi city, which is downstream from Minuma rice fields, was inundated. The water storage function of Minuma rice fields was reconsidered inspired by the Kanogawa typhoon, and "Minuma 3 principles," which does not allow using the farmland in Minuma rice fields for other purposes such as residential areas and industrial areas, was set in 1965; afterwards, the public land promotion policy was decided in the "Basic policy for sustainable management, use and preservation of Minuma rice fields" in 1995. After that, Saitama prefecture commissioned Saitama Agriculture & Forestry Corporation and civic groups to manage the public farmland acquired for Minuma rice fields public land promotion policy. Therefore, Saitama Agriculture & Forestry Corporation and civic groups are used as examples for this research. Saitama Agriculture & Forestry Corporation has implemented works for maintenance and management including mowing as preparation for tillage based on the discussion with the land owner, Saitama prefecture since they were commissioned management in 1998. First, the activities were conducted only by Saitama prefecture and Saitama Agriculture & Forestry Corporation, and they started from mowing, and cultivation of landscape amenity crops was added in 1999 in order to improve the landscape. Later on, activities such as hands-on farming experiences, communion (Fureai) farm for residents of the prefecture, agricultural prep school and School children\u27s farm, which is part of the hands-on farming activities were added one by one, and those activities accepted citizens, neighboring, residents, corporations and educational institutions to participate as user entities. In spite of the fact that the number of activities increased, the system that only one activity is allocated to one plot of public farmland has not changed, but multiple functions of farmland are exerted by one activity, and the farmland is therefore smoothly managed. Civic groups conduct activities in different ways. They decide the land management policy with Saitama prefecture, but the actual content of activities is decided by the civic groups. They have implemented multiple activities since they started maintenance and management of the public farmland, and multiple user entities including Kawaguchi city, civic groups other than the management entity, citizens, neighboring residents and corporations and sustaining entity have participated in them. In addition, multiple activities are allocated to one plot of public farmland, and as a consequence, various functions of farmland are exerted. As they continued organizing activities, the number of types of activities increased, and educational institutions were added to the original list of user entities, civic groups, citizens, neighboring residents and corporations. According to our survey, when the management entity implements multiple activities on one plot of public farmland, that means that multiple functions of farmland are exerted, and the farmland is thus smoothly maintained. The two case studies of an agriculture and forestry public corporation and a local civic group, revealed the fact that the sustainable management system of public farmland in a suburban area is a system which maintains the farmland by a combination of the following processes: (1) increase of land managing entities, (2) diversification of activities, (3) increase in the units of activity in farmland, and (4) increase in the range of functions of farmland. Although previous research on the sustainable management system of farmland concluded that the sustainable management system of private farmland is influenced only by the increase in the range of functions of farmland, the sustainable system could not be discussed only by increase in the range of functions of farmland in case of public farmland. The originality of this research is that it reveals the fact that the sustainable management system of public farmland involves a combination of processes (1)(2)(3)(4), and the flow of those processes are (1)→ (2)→(4) or (1)→(2)→(3)→(4), while the processes (1) and (2) lead to the process (4). Whether (3) is exited or not is not mandatory to the presence of the sustainable management system. Therefore, for the sustainable management system of public farmland, it is important to promote (1) and (2) and to promote activities concerning leisure of people and educational activities, because there are more activities related to them.首都大学東京, 2013-03-25, 博士 (観光科学), 甲第366号首都大学東
