A method for manufacturing a semiconductor wafer with a strained Si layer having sufficient tensile strain and few crystal defects, while achieving a relatively simple layered structure, is provided. The method includes the steps of: (a) forming an SiGe mixed crystal layer 12 and a first Si layer 13 in this order on the surface of a silicon wafer 11; (b) forming an SiO2 layer 16 on top of the first Si layer and/or a support wafer 14; (c) forming a layered product 17 by stacking the silicon wafer and the support wafer with the SiO2 layer being placed therebetween; (d) forming a second Si layer 18 by thinning the silicon wafer of the layered product; (e) implanting hydrogen ion and/or rare gas ion, such that ionic concentration peaks in a predetermined area; (f) subjecting the layered product to a first heat treatment; and (g) carrying out a second heat treatment following the first heat treatment, thereby relaxing the SiGe mixed crystal layer and diffusing Ge through portions of the first Si layer and the second Si layer.