To eliminate the need for swinging a nozzle main body in a reinforcing bar shaft direction by arranging the nozzle at each grid point of an assumed cube, facing the nozzles at a point symmetrical position of the cube to each other, and forming an ejection port so that a flame center line from a pair of the nozzles becomes a parallel flame.

A reinforcing bar is jointed, and an acetylene gas and oxygen are introduced into an induction tube body with a heating means while keeping an end face pressing condition by a pressing means, so as to eject a heating flame for pressing a reinforcing bar jointing end face from the nozzle. The nozzles are installed at upper and lower portions of four parallel induction tubes 221, 222, 223, 224 arranged at front, rear, right, and left positions sandwiching a reinforcing bar gas pressing portion, and are arranged at a grid point portion of an assumed hexahedron. The center lines of the flame from the point asymmetrical position nozzles are displaced from the center of the pressing portion so as to form a parallel crosses shape flame, and are crossed at the reinforcing bar pressing portion. Thus, the entire gas pressing portion is covered with the flame from each nozzle.