To ensure a large space by extremely removing waste in a material and spatial waste while improving quaking resistance.

The building frame of the No.1 unit 14 of the first floor of a unit house is composed of the four wall posts 222 fixed onto a ceiling panel 26, a floor panel 28 and ceiling girders 30, 32 and floor girders 38, 40. The wall post 222 has a function as 'a post, a wall and a brace', and can be installed at an arbitrary place. The overlapping of the post and a beam as the point at issue can be solved by gradually combining the units on the basis of the wall posts 222, and a large space can also be ensured. Since frame structure as seen in conventional devices is not formed, quaking resistance to lateral load is also improved.