An SiC substrate processing method includes a separation layer forming step of setting a focal point of a laser beam having a transmission wavelength to SiC inside an SiC substrate and next applying the laser beam to the SiC substrate to thereby form a separation layer inside the SiC substrate, the SiC substrate having a first surface and a second surface opposite to the first surface; a first plate attaching step of attaching a first plate to the first surface of the SiC substrate; a second plate attaching step of attaching a second plate to the second surface of the SiC substrate; and a separating step of applying an external force to the separation layer after performing the first plate attaching step and the second plate attaching step, thereby separating the SiC substrate into a first SiC substrate and a second SiC substrate along the separation layer.