Abstract Farm mechanization in Japan could be understood as a process brought a bout in the constellation of economic and political milieus of high economic growth. Labor productivity was raised to a degree unproportionate to the size of farming and yielded large amount of surplus labor power. This inherent contradiction became quite apparent after 1970. The expansion of non‐farm labor market absorbed the surplus labor power. Thus part‐time farming spreaded. changing the life pattern of farm families toward differentiation and individuation. A panel study at a rural community at the south‐western part of HONSHU enables us to compare the time allocation of family members before and after mechanization. After mechanization. time allocation pattern differentiated by generation and sex. Younger members have gained private spheres outside farming. The older are left at farm, working in the fields. However, the time allocation data collected at a rural community at the northeastern part of HONSHU tells that the differentiation and individuation was slow due to the under‐development of non‐farm l