Provided is a SiC substrate treatment method for, with respect to a SiC substrate (40) that has, on its surface, grooves (41), activating ions while preventing roughening of the surface of the substrate. In the method, an ion activation treatment in which the SiC substrate (40) is heated under Si vapor pressure is performed to the SiC substrate (40) has, on its surface, an ion implantation region (46) in which ions have been implanted, and has the grooves (41) provided in a region including at least the ion implantation region (46), thereby ions that are implanted in the SiC substrate (40) is activated while etching the surface of the substrate.