The consumption of various medical cares is affected not only by income and price but also by the number of household members. This study aims at examining how the number of household members affects the consumption pattern of medical care in Japan. The major findings of this study are summarized as follows; The elasticities of household members on the medical care consumption are estimated to be -2.4 in the 20-years groups in case of total medical care expenditure, 4.1 in the 50-years groups of medical care items, -3.1 in the 40-years groups of medical supplies and equipments, and -5.6 in the 60-years groups and -2.7 in the 50-years groups of medical services.