The purpose of this study is to investigate the actual conditions and causes of open space of multifamily housing around built-up areas in Tokyo. We sorted open space into two groups; inner and outer open space, and analyzed planning conditions of 59 housing samples. The pattern of inner and outer open space is various. The reason is architectural planning corresponded to various site patterns and following the Tokyo Metropolitan Building Safety Ordinance. The combination of inner and outer open space is 9 patterns. The most of these patterns has problems to plan rational open space in block.
