A method of manufacturing a semiconductor substrate in which an SiGe layer is grown epitaxially on a Si substrate, comprising: a first layer formation process of epitaxially growing a first SiGe layer on said Si substrate; wherein in said first layer formation process, the film thickness of said first SiGe layer is set to be thinner than twice the critical film thickness, which is the film thickness at which dislocations arise and lattice relaxation occurs due to increasing film thickness; a second layer formation process of epitaxially growing a second SiGe layer directly onto said first SiGe layer; and a heat treatment process of performing heat treatment of the substrate where the heat treatment is performed at a temperature exceeding a temperature of epitaxial growth of the first SiGe layer by temporally interrupting the epitaxial growth of the first SiGe layer during the first layer formation process, or performed at a temperature exceeding a temperature of epitaxial growth of the second SiGe layer by temporally interrupting the epitaxial growth of the second SiGe layer during the second layer formation process or after the second layer formation process; and characterized by a polishing process of removing the irregularities in the surface caused by said heat treatment by polishing the surface of the second SiGe layer after said formation of the second SiGe layer; and said second layer formation process comprises a first process of epitaxially growing SiGe gradient composition layer with Ge composition ratio increased gradually toward the surface; and a second process of epitaxially growing an SiGe constant-composition layer on said gradient composition layer at the final Ge composition ratio of the gradient composition layer, wherein both the first and second process is repeated in alternation a plurality of times at continuous Ge composition ratios, to deposit the second SiGe layer with Ge composition ratio changing in step-like fashion and having a gradient in the deposition direction; and wherein the Ge composition ratio at the bottom face of the second SiGe layer is made lower than the maximum value of the Ge composition ratio in said first SiGe layer. a first layer formation process of epitaxially growing a first SiGe layer on said Si substrate; wherein in said first layer formation process, the film thickness of said first SiGe layer is set to be thinner than twice the critical film thickness, which is the film thickness at which dislocations arise and lattice relaxation occurs due to increasing film thickness; a second layer formation process of epitaxially growing a second SiGe layer directly onto said first SiGe layer; and a heat treatment process of performing heat treatment of the substrate where the heat treatment is performed at a temperature exceeding a temperature of epitaxial growth of the first SiGe layer by temporally interrupting the epitaxial growth of the first SiGe layer during the first layer formation process, or performed at a temperature exceeding a temperature of epitaxial growth of the second SiGe layer by temporally interrupting the epitaxial growth of the second SiGe layer during the second layer formation process or after the second layer formation process; and