There is disclosed a method for manufacturing an SOI wafer comprising at least: implanting a hydrogen ion, a rare gas ion, or both the ions into a donor wafer formed of a silicon wafer or a silicon wafer having an oxide film formed on a surface thereof from a surface of the donor wafer, thereby forming an ion implanted layer; performing a plasma activation treatment with respect to at least one of an ion implanted surface of the donor wafer and a surface of a handle wafer, the surface of the handle wafer is to be bonded to the ion implanted surface; closely bonding these surfaces to each other; mechanically delaminating the donor wafer at the ion implanted layer as a boundary and thereby reducing a film thickness thereof to provide an SOI layer, and performing a heat treatment at 600 to 1000° C.; and polishing a surface of the SOI layer for 10 to 50 nm based on chemical mechanical polishing.A method for manufacturing with excellent productivity an SOI wafer having an SOI layer with a mirror-finished surface and high film thickness uniformity can be provided.