This article is presented with an intention of clarifying the transformation of the rural community after the World War II through a monographic study of the changes in life group (seikatsu gojo kankei) of the rural community. In the concrete, the approach is mainly to be made as to what the internal reaction has been in the replacing process from 'keiyakuko' to 'kyodokai'. In Tsugihashi the supreme prewar decisive organization used to be 'Tsugihashi keiyakuko'. In the new situations after the World War II, it had also a very important function by being deeply connected with 'Soshikai', which was newly formed as a group of the young generations or with 'Kayatanomoshiko' that consisted of 'Omodachiso'. About forty of the Showa era, however, the separation of the groups was very vividly seen and the desicive function has been gradually replaced by 'Tsugihashi kyodokai'. In other words re-integration has been very stronglypromoted in order to meet the needs of the new circumstances. This re-integration has internally brought about the financial unity and one Role system played by one 'Ie' unit.