Abstract: An automatic welding apparatus for forming a circular bead along a circumference of a first workpiece at its junction with a second workpiece in order to weld the former to the latter, comprising a turntable, clamp members for clamping the second workpiece to the turntable, a torch holder for holding a welding torch in an adjusted position, a torch positioner which is engageable with the first workpiece, for maintaining a constant relative positional relationship between the welding torch and the first workpiece, a positioner guide mechanism for supporting and guiding the torch positioner to a desired position in a plane extending in parallel relationship with respect to a surface plane of the turntable, and the torch holder being restricted from rotating.