PROBLEM TO BE SOLVED: To provide a new method of constructing houses to solve the problems of house structure becoming wet by rains or the roofing work at a high place.SOLUTION: A roof 16 is constructed beforehand, and then lifted up onto a house structure. Then the first floor, or the first and second floors, or the first floor through third floor (pillars, beams, etc. in the case of a wood frame structure, and walls in the case of a wall frame structure) are assembled. After that, the roof 16 is moved to the position for installation on the house structure and installed and fixed on it. When the first floor, or the first and second floor, or the first floor through third floor are assembled, the roof 16 has already been lifted up and can minimize the wetting of the house structure by rains.