Nagaya is one of the traditional Japanese housing types in which multiple houses are attached together. In Nagaya, walls are shared by several houses but entrances are privately owned by houses. Nagaya consists of many wooden houses for common people located in parallel with narrow alleys between them. Nagaya was one of the representative housing types in Japanese architectural history. This research is to study the background of the origination of Nagaya in Japan, the characteristics of space and land planning, the features and causes of the changes in the space and land planning. In this research, we observed and analyzed unit plans of a block of gate-type Nagayas in Hanan, Osaka. The results are as follows. First, as the inner alleys(Roji) are closed, the number of entrances to each housing lot decreased from two to one since one entrance that used to be open to inner alleys(Roji) are permanently closed. Second, walls between streets and housing lots which used to be one of the outstanding characteristics of gate-type Nagayas are disappearing. Third, as the bathrooms are added to houses, the front gardens are being degraded to empty spaces or sometimes totally removed. Fourth, the space in the first floor of houses become family spaces, and that in the second floor is divided into private rooms for individuals.