MIG welding method and MIG welding device

A MIG welding device that forms a molten pool on a metal member to be welded, the MIG welding device comprising:

• a pair of MIG electrodes whose current values are individually variable and that include at least one MIG electrode through which a pulse current is passed;
• a moving unit that moves the pair of MIG electrodes in a welding direction;
• a gas supply unit that supplies a shield gas between the pair of MIG electrodes and the metal member to be welded;
• and
• a control unit that controls welding by the pair of MIG electrodes and movement of the pair of MIG electrodes by the moving unit,
• wherein the control unit repeatedly executes:
• a first control that includes passing a current having substantially the same current value through the pair of MIG electrodes, so that an arc of a first MIG electrode of the pair of MIG electrodes generates a cathode spot in front of the molten pool in a moving direction, and the arc removes an oxide on a surface of the metal member to be welded;
• and
• a second control that includes:
• passing a pulse current having a higher current value than that of the first MIG electrode through a second MIG electrode of the pair of MIG electrodes, so that cathode spots are each generated within the molten pool to newly form a molten pool;
• and performing welding within an area while the pair of MIG electrodes are moved in the welding direction by the moving unit to move a cathode spot to the newly formed molten pool, the area being an area where the oxide on the surface of the metal member to be welded is removed.