The object of this study is to clarify the construction and historical trends of living space, concentrating on Naisho or inner space found in Goto City, Nagasaki Prefecture, Japan. The investigation was made principally by field study of 158 homes in 7 districts in Goto City. Analysis was made of the floor plan and age of respective homes as well as the names given to rooms by the occupants. How the rooms were used daily as well as on special occasions was also analyzed. Attension was paid particularly to the peculiarities of Goto City with regard to the meaning of the names given to Naisho by the occupants, the relationship to other rooms, and what was found in Naisho. Results: 1. Of the four-room types, which included Naisho, the oldest home was built in 1925 and the latest in 1968, both located in Sakiyama. 2. Naisho in the homes built between 1924 and 1968 were arranged inside Adanoma or outer room. Naisho was arranged as a corridor or passage to Nando or storage space. In other words, Naisho was separated from Zasiki or normal room. It is to be noted that there were the dining and living rooms adjacent to Naisho. 3. It became clear that the homes with Naisho are a feature peculiar to Goto City as they are found in all the seven districts under study. 4. Nai of Naisho means inner or inside as against Ada or Adanoma meaning outer or outside. Naisho also means entrance to the inner space. 5. Prior to 1924 Naisho in Goto City was used as cooking space, and after 1924 it began to be used as dining and living space as well.
