Laser processing device (1) includes: laser-beam switching apparatus (70) that switches between a first optical path and a second optical path as an optical path along which a laser beam is to travel, the first optical path including first fiber (11), the second optical path including second fiber (21) that has a core diameter that is larger than a core diameter of first fiber (11); and processing head (80) that illuminates a same processed point on workpiece (900) with a laser beam that has passed through the first optical path or the second optical path. When illumination with laser beam that has passed through the first optical path is performed for a predetermined period of time, laser-beam switching apparatus (70) switches from the first optical path to the second optical path.