Abstract
This paper is concerned with a house in which two familis are living together. The space organization must manifest relationship of two families, as a whole. The main findings are : 1) as for family structure, three generations which consist of children, parents and grandparents live in a house. This phenominon shows the idea of the household system in the old Civil Code in the Japanese society; 2) the typical type of the house is a two-story on with a dependent entrance and bath, where one family can live above and another below; 3) as the number of dependent spaces such as an entrance hall, a bathroom, a kitchen and a living room increases, the activities of cooking, eating and relaxing come to be done together between two families. Moreover even family economics becomes dependent as well. The space organization of the house for two families reflects the degree of association of them in daily life, that is, the greater degree of association two families want, the more common spaces in a house they demand.
