PURPOSE: To simply and easily construct a tough building by connecting plural heart members with a fixed space apart from each other, and covering the heart member with a surface seat to form a hollow prearranged member of a building, and applying synthetic resin to the surface seat.

CONSTITUTION: Plural heat members 1 formed of vertical parts 1A provided on both sides and a horizontal part 1B to mutually connect the upper ends of the parts 1A are mutually connected at fixed spaces. Next, the heat member 1 is covered with a bendable surface seat 2, which is tightly bound using a binder cord 3 to adhere to the heart member 1. Thus a hollow prearranged member of a building is formed. Synthetic resin is then applied to the surface seat 2 to form a synthetic resin coat layer 4 of fiber reinforced plastics, and a sufficiently tough building can be therefore constructed. Thus the building can dispense with a big pillar inside itself to be used with a wide space kept in its inside, and moreover the walls and roofs of the building can be unitedly constructed without a joint to extremely reduce a leak in the roof.