To provide a building that can make effective use of a site at the boundary to a north adjacent site in securing its floor area.

In this building 1, a lower story 3 is provided at the boundary A of a building main body 2 to a north adjacent site. Thus, within the limit of a north oblique line, the lower story 3 can be brought close to the boundary A to the north adjacent site. The building 1 as a whole is therefore not separated from the boundary A to the north adjacent site and the part of the site at the boundary A to the north adjacent site can be used effectively in securing the floor area of the building 1.