PURPOSE: To enable labor to be saved on the execution of work, and enable the term of construction to be shortened, at the same time keeping high precision by setting mass-production members in a factory and the precut members, to be architectural material.

CONSTITUTION: On a concrete foundation, the sill members 1 of precut joint sections and connection sections are fixed, and a sill is formed. On the sill, the precut column material 2 of the joint section, the connection section, and wooden wall material worked to be fixed are assembled with each other, an with sections between the columns 2, precut thick wooden wall materials 3 are combined, and they are raised, first floor columns and wall materials are formed. Also on second and third floor sections, in the same manner, completely precut thick wooden wall materials 3' are combined with sections between column materials 2', and they are raised, and second and third floor column and wall materials are formed. On a roof truss, the work of thick wooden plates as roof bed material without rafters is executed, and the work of a roof bed is executed. On flooring for first, second, and third floors, directly on sleeper material without joists, the work of previously decorated thick floor material is executed, and the work of the floors is executed.