Abstract: There is provided a method of fabricating an SOI wafer having high quality by hydrogen ion delamination method wherein a damage layer remaining on the surface of the SOI layer after delamination and surface roughness are removed maintaining thickness uniformity of the SOI layer. According to the present invention, there are provided a method of fabricating an SOI wafer by hydrogen ion delamination method wherein an oxide film is formed on an SOI layer by heat treatment in an oxidizing atmosphere after bonding heat treatment, then the oxide film is removed, and subsequently heat treatment in a reducing atmosphere is performed; a method of fabricating an SOI wafer by hydrogen ion delamination method wherein an oxide film is formed on an SOI layer by heat treatment in an oxidizing atmosphere after delaminating heat treatment, then the oxide film is removed, and subsequently heat treatment in a reducing atmosphere is performed; and an SOI wafer fabricated by the methods.