The SHIMODERA-NITTO improved dwellings were built by the slum clearance program before World War II. The aim of this study is to analyze the management and occupation of the common space of the dwellings. From the study followings are summarized. The common exterior space is occupated by extensions of private commodities. The ways of occupation are decided by the dwellers' consciousness and by the type and story of the dwellings. The levels of the occupation of the common space are divided into five, and the ways of use are discussed.