To rationalize the bar arrangement of beam main reinforcement in a column and beam connection part and improve structure performance of the connection part.

Beam main reinforcement 3 constituted of twisted reinforcement is inserted in each vertical frame piece 2 of a rectangular frame type column and beam connection part shear reinforcement band steel plate 1 in the form of an ornamental hair pin, a column and beam connection unit P tightened through nuts 4 is set on the head part of a column A. A reinforced concrete- made large beam B is mounted on the head part of the column A, and the main reinforcement of the beam lower end of the large beam B is jointed to the beam main reinforcement 3 composed of the twisted reinforcement.