PURPOSE: To accurately teach the welding position to industrial robots by setting the data of the position and direction of welding electrodes on a controller of one robot, then, transferring these to a controller of the other robot and driving the other robot to move the welding electrodes to the welding position.

CONSTITUTION: After the controllers 11 and 21 of the plural industrial robots 1 and 2 are set on the teaching mode, the one industrial robot 1 is subjected to teaching operation and the data of the position and direction of the welding electrode 103 for materials 3 to be welded are set on the controller 11 thereof. The data of the position and direction set on the one controller 11 are then transferred to the other controller 21. While the other industrial robot 2 being subjected to teaching operation based on the transferred data, the other welding electrode 203 is then made in a coaxial state with the one welding electrode 103 and the materials 3 to be welded are held almost orthogonally by these electrodes.