This paper aims to explain the mechanism of the transfer of farming rights in Japan's large-scale upland farming belt by focusing on the social relationships among farmers. The mechanisms of farmers' social relationships were analyzed by applying the concept of "multiplex-uniplex" that is used in the social network approach. The study area was Omaki and Kowa settlements in central Hokkaido Prefecture. This area was newly cleared and opened for settlement in 1950. The major agricultural enterprises in this area are upland, dairy, and vegetable farming. The main findings are as follows. 1) Various social relationships among farmers were observed behind the transfer of farming rights, including territorial relations, kinship and school connections. Some official agencies were also involved in these relationships. 2) The types of social relationships varied in the way the transfer of farming rights overlapped. Almost all transfers were influenced by multiplex relationships, such as a combination of territorial relations, kinship, and school connections. On the other hand, uniplex relationships existed in the transfer of farming rights when farmers did not have these social relationships. 3) Social relationships in the transfer of farming rights expanded spatially from the scale of the neighborhood or settlement to the scale of the home district, other districts, and outside of town. Many farmers accumulated most of their farmland within their settlements, but depending on farm management conditions, some late accumulated farmland was located outside their settlements.