A method of manufacturing an SiC single crystal wafer according to the present invention includes the steps of: (a) preparing an SiC single crystal wafer 10 with a mirror-polished surface; (b) oxidizing the surface of the SiC single crystal wafer 10 with plasma, thereby forming an oxide layer 12 on the surface of the SiC single crystal wafer; and (c) removing at least a portion of the oxide layer 12 by a reactive ion etching process. Preferably, the surface of the wafer is planarized by repeatedly performing the steps (b) and (c) a number of times.