The present application aims to provide a surface treatment method that is able to accurately control the rate of etching a single crystal SiC substrate and thereby enables correct understanding of the amount of etching. In the surface treatment method, the single crystal SiC substrate is etched by a heat treatment performed under Si vapor pressure. At a time of the etching, inert gas pressure in an atmosphere around the single crystal SiC substrate is adjusted to control the rate of etching. Accordingly, correct understanding of the amount of etching is obtained.