PURPOSE: To improve yield strength by arranging main reinforcements to be jointed, to be confronted with each other at a specified interval, and by jointing the reinforcements to be spirally fitted with jointing bolts with the strength higher and the cross-sectional areas smaller than those of the respective main reinforcements.

CONSTITUTION: At a capital section and a base section with the bending moment of a reinforced concrete column, to be the largest, a main reinforcement 1 and other main reinforcements 1' are arranged to be confronted with each other at specified intervals. Then, jointing bolts 3 with the strength higher and the cross-sectional areas smaller than those of the respective main reinforcements 1, 1' are spirally fitted into the female screw holes of the respective main reinforcements 1, 1'.