PURPOSE: To increase the supporting strength, by forming fitting holes for a column base on the base plate and placing a connection plate to fix the column base on the surface of the base plate.

CONSTITUTION: A fitting hole 12 forming a square ring-shape is made in the center of the upper face of a base plate 11 and an inner connection plate 13 is provided as a unit along the full inner periphery of the fitting hole 12. And an outer connection plate 15 is provided as a unit along the full outer periphery of the fitting hole 12 to form a column base metal fitting 1. Next, the lower end of a column base B is forced to pass through between the inner connection plate 13 of the column base metal fitting 1 and the outer connection plate 15 to fit in the fitting hole 12 and fixed on a metal fitting 1 by a bolt E screwed in the screw hole 14 of the inner connection plate 13 through the bolt insertion hole 16 of the outer connection plate 15 and the hole B1 of the column base B. Next, the column base B is erected on the foundation concrete A and the base plate 11 is fixed by the anchor bolts C and nuts D.