The most densely populated area in the twenty-three wards of Tokyo is identified as a zone of five to ten kilometers which is centered at Shimbashi station by using Small Area Statistics of 2010 Population Census of Japan. This paper analyses the characteristics of population, households, and dwelling houses in 5 to 10 kilometer zone, comparing with inner and outer zones. It becomes clear that the high densely populated circular area of 5 to 10 kilometer zone is formed by one-person households of 20 age and 30 age groups residing in small apartments of floor space less than 49 square meters and the medium- and high-levels layer.
