There is an opinion which insists that farming people of Japan are gradually divided into many landed labors and a few entrepreneurial farmers. But the mobility of land either by transfer or by tenancy has been very weak until now, and some agricultural economists have had doubts about the opinion. In such a situation, the eyes of many agricultural economists have been turned on another opinion, according to which the agriculture of Japan could not continue to exist without group farming. But we can not neglect the third opinion, according to which group farming is so transitional that the group gradually is dissolved into landed or landless laborers and entrepreneurial farmers. So, it is important to make our effort to explain which opinion is correct. The present paper deals with planning problems in the course of development of hamlet group farming. And the purpose of this study is to examine the possibility of finding expansive solutions for the problems, from the viewpoint of mathematical theory of planning, through a case study of group farming of Nakae Hamlet in Oita Prefecture by linear programming method. Findings of this study are summarized as follows. 1. In the first stage of hamlet group farming, where the degree of interdependence of farmers is the least, the full-time farmers are subject to severe restrictions in obtaining arable land and hired labor for their own farm managements, and in introducing efficient combinations of production activities into their own farm managements. While, the part-time farmers are subject to severe restrictions in cutting down the fixed costs of their own farm managements, the greater part of which is depreciation expenses of agricultural machinery and equipments. 2. To relieve these severe restrictions in cooperation with one another, and to make efficient use of their productive resources on their own responsibility, they go on to the next more intensive stage of hamlet group farming. It is clear that those severe restrictions are largely relieved and their productive resources are efficiently used to raise their aggregate income, if hamlet group farming of this stage is carried out smoothly as planned. But raising their aggregate income is one thing, raising their individual income is another, and the clash of interests may occur among them. So, the result of hamlet group farming depends largely on how well the interests are adjusted among them. Generally speaking, it is not easy to adjust the interests among them, especially without an able leader. 3. To make a more efficient and more realistic group farming plan, and to make the defects of the plan more clear, quantitative analysis as well as qualitative analysis of the plan are necessary. Linear programming method is useful to make quantitative analysis of the plan.