UNIT BUILDING

PROBLEM TO BE SOLVED: To adequately conform to the setback restriction by the building code by placing an upper floor building unit on a lower floor building unit in such a manner than the upper floor building unit is set back from the lower floor building unit in both the building length and width directions. SOLUTION: A first floor building unit 11 and a second floor building unit 12 are made to the building units having the same size, and the third floor building unit 13 is made shorter in both the width and length directions compared to the first and second building units 11, 12. And mutually neighboring two sides 42A, 42B at the floor 42 of the third floor building unit 13 are made flush with the mutually neighboring two sides 14A, 14B at the ceiling 14 of the second floor building unit 12 when locating the third floor building unit with a setback. Then, for the second floor building unit 12, a reinforcing beam 15 at the ceiling 14 is extended and installed in a girder direction (length), also a reinforcing column 17 is installed in a wall 16, and a load of the third floor building unit 13 acting to the reinforcing beam 15 is transferred to the floor 18 of the second floor building unit 12. Thus, the building site can be utilized effectively with a low-priced construction.