The present invention is a method for producing an SOI substrate including the steps of: preparing a bond wafer and a base wafer which are composed of single crystal silicon wafers; forming an oxide film on a surface of at least one of the bond wafer and the base wafer so that a thickness of a buried oxide film after bonding becomes 3 μm or more; bonding the bond wafer and the base wafer via the oxide film; performing a low-temperature heat treatment at a temperature of 400° C. or more and 1000° C. or less to the bonded substrate; thinning the bond wafer to be an SOI layer; and increasing bonding strength by performing a high-temperature heat treatment at a temperature exceeding 1000° C. Thus, a method for producing an SOI substrate by which generation of slip dislocations is suppressed and an SOI substrate having a high-quality SOI layer can be obtained, for producing a SOI layer in which the thickness of a buried oxide film is thick as 3 μm or more by a bonding method, etc. are provided.