PURPOSE: To shift molten metal in the state of small lump without stopping a large quantity of molten metals at the tip of a wire, and to stabilize the arc preventing generation of spatter by changing speed of feeding of the welding wire in synchronization with the period of pulse current.

CONSTITUTION: In consumable electrode type pulse arc welding, the welding wire 12 is melted by a welding arc 21 and forms molten metal 12a. The molten metal 12a is accumulated at the tip of the wire 12, and at the same time, the wire 12 is fed toward an object to be welded 14. At this time its current value increases. From this state, the feeding speed of the wire 12 is reversed. That is, the wire 12 is shifted in the direction going away from the object to be welded 14, and the molten metal 12a is separated and shifted forcibly by inertia. As force of inertia due to change of feeding speed of the wire is given to the molten metal 12a in addition to pinch effect of pulse peak current, sure separation and shifting are made from the state of small lump. Accordingly, a beautiful bead free from welding defect can be obtained.