Provided is a laser machining method in which, when modified regions are formed plural number of times by changing the depth in the thickness direction of a substrate, displacement of the formed modified regions from a planned cutting line is inhibited. Specifically provided is a laser machining method for cutting a substrate (10) into chips. Modified regions are formed at a deep distance (d1) inside the substrate from the entrance surface of a laser beam by first scanning (a) in which the substrate is scanned with the laser beam along a planned cutting line (21a) in the X direction of the substrate and second scanning (b) in which the substrate is scanned with the laser beam along a planned cutting line (21b) in the Y direction. Modified regions are again formed at a shallow distance (d2) (d1>d2) inside the substrate by third scanning (c) in which the substrate is scanned with the laser beam along the planned cutting line (21a) in the X direction and fourth scanning (d) in which the substrate is scanned with the laser beam along the planned cutting line (21b) in the Y direction. The third scanning is performed by scanning from a U end portion at the periphery to the center and scanning from a D end portion at the periphery to the center.