PURPOSE: To reduce the time for restarting welding and to make an operation more efficient in the stage of performing welding with a robot by detecting the arc interruption at which the wire itself sticks to the welded part and performing treatment for the arc interruption such as cutting of the wire thereby enabling restarting of welding.

CONSTITUTION: A titled method in a robot welding machine which generates an arc from the top end of a wire and welds the welding part consists of a step for storing successively the passages where the wire moves and detecting the interruption of the arc, a step for cutting the wire in accordance with said detection and retreating the wire, a step for feeding and retreating the wire, and a step for resuming the welding when the contact between the wire and the welding member is interrupted. The above-described wire is fed until it contacts with the welding member and is then retreated until it loses the contact in the step for feeding and retreating the wire. Even if the arc is interrupted by melt sticking of the wire to the welding member, the welding is immediately restarted by the above-mentioned method.