A method for manufacturing a strained silicon wafer, having steps of a first step of preparing a single crystal silicon substrate, a second step of forming a graded SiGe layer on the substrate, the graded SiGe layer having a first Ge composition ratio increased stepwisely from 5 to 60% at atomic ratio, a third step of forming a SiGe constant composition layer on the graded SiGe layer, the SiGe constant composition layer having a Ge composition ratio substantially equal to the Ge composition ratio on a surface of the-graded SiGe layer and a fourth step of forming a strained Si layer on the SiGe constant composition layer. The second through fourth steps are performed under the reduced pressure atmosphere while the single crystal silicon substrate is rotated in a circumferential direction at a rate from 300 rpm to 1500 rpm.