MANUFACTURING METHOD OF GALLIUM NITRIDE SUBSTRATE

A manufacturing method of a gallium nitride (GaN) substrate includes a peeling layer forming step of forming a peeling layer at a depth, which corresponds to a thickness of the gallium nitride substrate to be manufactured, by relatively moving a GaN ingot and a focal point of a laser beam of a wavelength, which transmits through GaN, along a direction of a crystal orientation of the GaN ingot as represented by the below-described formula (1) with the focal point positioned inside the GaN ingot, and a peeling step of peeling the GaN substrate from the GaN ingot using the peeling layer as a start point. The peeling layer forming step is set such that the laser beam is split to form a plurality of focal points and straight lines connecting the individual split focal points each extend along a direction parallel to the direction of the crystal orientation represented by the below-described formula (1).1 1 2 0 Formula (1)