PURPOSE: To provide the multilayer automatic welding equipment and its welding method of the all position reinforcing bars as the automatic reinforcing bar joint producing method in reinforcing bar work.

CONSTITUTION: The reinforcing bar end face is formed into a conical groove 19 and fixed by a reinforcing bar fixing jig 20, divided discoid materials 1 and 2 are combined by fastners 3 and 4, the multilayer automatic welding equipment is set up on a vice A15, the position of a welding torch 7 is adjusted by a position correcting device 11 and the inner peripheral surfaces of divided cylindrical materials 5 and 6 are rotated with these along the outer peripheral parts of the reinforcing bars by rotating the multilayer automatic welding equipment. The welding torch 7 is then rotated with a reinforcing bar axis as a center by rotating around the reinforcing bar axial center via a first surface gear 12 to rotate in synchronization by a second surface gear 13 with the output of a driving motor 14, the welding wire tip follows the inside of a reinforcing bar groove and cladding by welding is performed on the groove inside from the axial center of the reinforcing bars by regular and reverse rotation by using the gas shielded arc welding method, etc.