A laser processing apparatus 1 is an apparatus for forming a modified region R in an object to be processed S by irradiating the object S with laser light L. The laser processing apparatus 1 comprises a laser light source 2 that emits the laser light L, a mount table 8 that supports the object S, and an optical system 11 that converges a ring part surrounding a center part including an optical axis of the laser light L in the laser light L emitted from the laser light source 2 at a predetermined part of the object S supported by the mount table 8. The optical system 11 adjusts a form of at least one of inner and outer edges of the ring part of the laser light L according to a position of the predetermined part in the object S.