There is disclosed a method of fabricating an SOI wafer in which a bond wafer to form a SOI layer and a base wafer to be a supporting substrate are prepared; an oxide film is formed on at least the bond wafer; hydrogen ions or rare gas ions are implanted in the bond wafer via the oxide film in order to form a fine bubble layer (enclosed layer) within the bond wafer; the ion-implanted surface is brought into close contact with the surface of the base wafer; and then heat treatment is performed to separate a thin film from the bond wafer using the fine bubble layer as a delaminating plane to fabricate the SOI wafer having an SOI layer; and wherein deviation in the thickness of the oxide film formed on the bond wafer is controlled to be smaller than the deviation in the ion implantation depth, and the SOI wafer fabricated thereby. There is provided an SOI wafer which has an SOI layer having improved thickness uniformity.