PURPOSE: To sharply improve the working efficiency for jointing panels.

CONSTITUTION: Face materials 1b, 5b at the end sections to be jointed of a first-floor wall panel 1 and a second-floor wall panel 5 are notched in advance. Jointing members 12 are coupled and fixed to recesses 11 formed when both wall panels 1, 5 are brought into contact with each other, and both wall panels 1, 5 are jointed. Lintel members 13 are fixed to both side sections at the lower end section of an inner wall panel 7 in advance, and notch sections 14 are formed at edge sections on the lower side of floor panels 3. The notch sections 14 of the floor panels 3 are coupled and fixed to the lintel members 13 and jointing members 12, and the floor panels 3 are suspended on the wall panels 1, 5 and the inner wall panel 7 to constitute the floor.