To facilitate setting of welding conditions when wire for CO2 gas arc welding is used instead of wire for pulse arc welding in MAG pulse welding.

In a setting method of the welding conditions of the MAG pulse welding, which is carried out by feeding welding wire 1 at a preliminarily determined feeding speed Fr, applying a peak current Ipr during a peak period Tpr, applying a base current Ibr during a base period, and controlling the base period to allow a welding voltage average value Vd to be equal to a welding voltage setting value Vr, a wire type selection switch ST for selecting a wire mode for CO2 gas arc welding is arranged, and when this mode is selected, the peak period Tpr is made longer by a predetermined value Tp, while the welding voltage setting value Vr is increased by a predetermined value Vr, and the feeding speed Fr is made faster by a predetermined value Fr. Accordingly, the welding conditions suitable for the wire for CO2 gas arc welding are automatically set only by selecting the switch ST.