A method of manufacturing a semiconductor substrate includes a growing step of growing a second single crystalline semiconductor on a first single crystalline semiconductor, a blocking layer forming step of forming a blocking layer on the second single crystalline semiconductor, and a relaxing step of generating crystal defects at a portion deeper than the blocking layer to relax a stress acting on the second single crystalline semiconductor. The blocking layer includes, e.g., a porous layer, and prevents the crystal defects at the portion deeper than the blocking layer from propagating to the surface of the second single crystalline semiconductor.