Abstract: A material that is useful as a wear-resistant member, a highly functional photocatalytic material, a photoelectric conversion element material, etc., is produced without the need for complicated processes or complicated handling, which are problems of the prior art. Provided is a method for producing a surface-treated metallic titanium material or titanium alloy material, the method comprising the steps of (1) forming titanium nitride on the surface of a metallic titanium material, and (2) heating the metallic titanium material with titanium nitride formed on the surface thereof obtained in step (1) in an oxidizing atmosphere.