This paper aims to clarify the following from the viewpoint of agriculture and trend toward farm households earning income from other jobs. 1) The formation factors of three-generation households. 2) Difference of changes in households composition for the elderly by difference of the factors. The conclusions are as follows. 1. The formation factors of three-generation households are farm households earning income from other jobs, urbanization, degree of secondary/tertiary industry, rice crop. 2.Trend to changes in households composition for the elderly are not different. However, changes in number of aged-couple households and aged-single-persons are different by difference of the factors.
