A method for manufacturing a bonded SOI wafer, including depositing a polycrystalline silicon layer on a base wafer, forming an insulator film on a bond wafer, bonding the bond wafer and a polished surface of the silicon layer with the insulator film interposed, and thinning the bond wafer, wherein a silicon single crystal wafer having a resistivity of 100 Ω·cm or more is the base wafer, the step of depositing the silicon layer includes a stage of forming an oxide film on the surface of the base wafer, and the silicon layer is deposited between 1050° C. and 1200° C. Accordingly, the method enables a polycrystalline silicon layer to be deposited while preventing the progress of single crystallization even through a heat treatment step in the SOI wafer manufacturing process or a heat treatment step in the device manufacturing process and can improve throughput in the polycrystalline silicon layer depositing step.