A pulse welding period includes a first peak period for supplying a first peak current to a welding wire, a first base period for supplying a base current smaller than the first peak current to the welding wire, a second peak period for supplying a second peak current to the welding wire after alternately repeating the first peak period and the first base period (n−1) times (n is an integer equal to or larger than 2), and a second base period for supplying the base current to the welding wire. The second peak current is larger than the first peak current, and droplets are transferred from the welding wire during the second peak period or the second base period.