LASER MACHINING METHOD AND LASER MACHINING DEVICE

Provided are a laser machining method and a laser machining device that can form a large number of fine grooves on a surface of a base material. A laser machining method and a laser machining device according to the present invention include: emitting a beam of laser light in a form of pulse from each of a plurality of laser emitting ends into a space, the plurality of laser emitting ends being arranged separately from each other; making a plurality of beams of the laser light incident on a light collection optical system that reduces a gap between the beams of the laser light to such an extent that the plurality of beams of the laser light are prevented from intersecting each other on a surface to be machined; irradiating the surface to be machined with the plurality of beams of the laser light emitted from the light collection optical system to form a plurality of focused spots separated from each other in a first direction, the plurality of focused spots each causing ablation; and moving the light collection optical system and the surface to be machined relative to each other both along the surface to be machined and in a second direction orthogonal to the first direction to simultaneously form a plurality of grooves on the surface to be machined.