A planar object to be processed 1 comprising a hexagonal SiC substrate 12 having a front face 12a forming an angle corresponding to an off-angle with a c-plane is prepared. Subsequently, the object 1 is irradiated with pulse-oscillated laser light L along lines to cut 5a, 5m such that a pulse pitch becomes 10 μm to 18 μm while locating a converging point P of the laser light L within the SiC substrate 12. Thereby, modified regions 7a, 7m to become cutting start points are formed within the SiC substrate 12 along the lines 5a, 5m.