There is provided a target object processing method capable of self-breaking a target object with a laser beam. The target object processing method includes: generating a laser beam from a laser beam source; correcting a divergence angle of the generated laser beam; and forming a spot by condensing the corrected laser beam to the inside of the target object. A shape or a size of the spot is adjusted by correcting the divergence angle of the laser beam, a phase transformation area is formed within the target object by the spot, and the target object is subject to self-breaking with the phase transformation area as the starting point.