Laser welding method and laser welding device

A laser welding device comprising:

• a laser oscillator that outputs a laser beam;
• a laser head through which a first workpiece and a second workpiece are irradiated with the laser beam, the first workpiece and the second workpiece being stacked on each other, each of the first workpiece and the second workpiece having a surface coated with a first material, each of the first workpiece and the second workpiece being made of a second material, the second material differing from the first material;
• a robot equipped with the laser head;
• and
• a control unit that controls an output of the laser oscillator, an operation of the laser head, and an operation of the robot,
• wherein a first region in which the first workpiece and the second workpiece are stacked on each other is irradiated with a laser beam so that the laser beam penetrates both the first workpiece and the second workpiece, and
• a second region including the first region is irradiated with a laser beam in a spiral fashion.