Provided is a laser processing device capable of performing high-power laser processing while preventing reduction of life duration of a light source for excitation light. By collecting the light emitted from single emitters of a plurality of single emitter LDs onto one end face of an optical fiber cable, high-power excitation light is transmitted to a marking head through the optical fiber cable. Excitation light emitted from the other end face of the optical fiber cable is separated into first excitation light and second excitation light. The first excitation light excites a first laser medium to generate laser light. The generated laser light enters a second laser medium. The second excitation light enters the second laser medium. With this, the second laser medium is excited, and the laser light that has entered the second laser medium from the first laser medium is amplified.