PURPOSE: To make small the foundation to have a precast concrete column stand of itself and beam sections continued to the foundation and to make it possible to obtain high stress.

CONSTITUTION: A square columnar section 11 having a mortise 13 inserting a pre-cast concrete column 20 thereon is provided on the foundation body 12, and U-shaped upper end reinforcing bars 16a and 16b are buried in arrangements surrounding three sides of the upper end of the square columnar section 11. Upper main reinforcing bars 17a and 17b of beam sections 14a and 14b are inserted and buried between the U-shaped both end sections by overlapping them in the direction of the beam widths.