PURPOSE: To remarkably reduce interference between the cable of an end effector and an arm and that between a work and the arm by bending a second link in its center at a substantially right angle, and setting the fore half of the bent second link and a third link in substantially horizontal and vertical attitudes in the centers of their action ranges.

CONSTITUTION: Out of links 8, 9 in an articulated type arm, the second link 8 located farther apart from a torch 14 serving as an end effector is bent in its center at a substantially right angle. The fore half of the bent link 8 and the third link 9 are set in substantially horizontal and vertical attitudes in the centers of their action ranges, respectively. As a result, the second link 8 can go round a work 17 without any interference, and as well, the third link 9 having the vertical standard attitude can be prevented from the interference with the cable 13 of the torch 14.