Provided is a method for manufacturing an SOI wafer, which is capable of: efficiently removing an ion-implanted defect layer existing in an ion implanted layer in the vicinity of a peeled surface peeled by an ion implantation peeling method; ensuring the in-plane uniformity of a substrate; and also achieving cost reduction and higher throughput. The method for manufacturing an SOI wafer includes at least the steps of: bonding a silicon wafer with or without an oxide film onto a handle wafer to prepare a bonded substrate, wherein the silicon wafer has an ion implanted layer formed by implanting hydrogen ions and/or rare gas ions into the silicon wafer; peeling the silicon wafer along the ion implanted layer, thereby transferring the silicon wafer onto the handle wafer to produce a post-peeling SOI wafer; immersing the post-peeling SOI wafer in an aqueous ammonia-hydrogen peroxide solution; and performing a heat treatment at a temperature of 900° C. or higher on the immersed post-peeling SOI wafer, and/or polishing a silicon film layer of the immersed post-peeling SOI wafer, through CMP polishing by 10 to 50 nm.