Abstract: An automatic welding machine of a type, in which a welding torch is subjected to predetermined three-dimensional locus motions by means of three profile cams for controlling movement of the torch in the left-and-right, up-and-down, and front-and-back directions in accordance with predetermined programs set in the machine, the machine being constructed with (a) a driving section including a frame to support component members thereon, a shaft rotatably held on the frame, an electric motor axially fitted at one end of the shaft, a plurality of profile cams fixedly provided on the other end part of the shaft so as to be rotated therewith, the cams being arranged with an appropriate space interval between them, and cam follower members corresponding in number to the profile cams and intimately contacted with the cams to move in accordance with rotational movement of the cams; and (b) a driven section including a frame to support component members thereon, a plurality of movable members in the left-and-right, up-an