The primary unit of social organization in Japan is the household. Whatever the composition of a household may be, its basic structure is always in terms of this principle. The organization of a community in rural Japan is built only on the basis of the household, not on the individual of the family, or on the descent group. Thus the ie is the most important structural element in the analysis of kinship and economic organization in rural Japan. So far the author has presented the interpretation and generalizations from the available ethnographic data of the inkyo system, with particular reference to the household succession rule. The inkyo system offers the best solution for such a conflict. Normally the transmission of the office of mistress is parallel to the transmission of the headship, though it does not necessarily take place at the same time—it may be delayed.