A laser processing device includes a laser light source, a converging optical system, a controller, and a reflective spatial light modulator. The controller and the reflective spatial light modulator, while using an aberration as a reference aberration, the aberration occurring when laser light is converged at a converging position with an amount of aberration correction in a state in which an ideal converging position is shifted by a predetermined distance to a laser light entrance side from the converging position, adjusts the aberration such that a first converging length longer than a reference converging length of the reference aberration is obtained and a first converging intensity less than a reference converging intensity of the reference aberration is obtained, when a modified region is formed within a first region closest to a front face of an object to be processed.
