PURPOSE: To significantly improve constructing period and constructing cost, and construct a building structure by all-weather construction method.

CONSTITUTION: In a site to construct a building structure, a plurality of masts 1 are stood. A climb table 10 capable of rising and lowering from about the ground surface to the mast top part and having a working floor of a prescribed area is arranged every mast 1. A flat slab is assembled on the working floor of each climb table 10 situated near the ground surface. The flat slabs situated to a mast height forming a prescribed floor by the rising of the climb table 10 are mutually connected to construct a floor part 12. The climb table 10 is then lowered to near the ground surface. The assembling of another flat slab on the working floor to the connection of the flat subs in a prescribed height are repeatedly carried out, whereby the floor part of the top floor is preferentially constructed, and the floor parts of the lower floors are thereafter constructed.