To obtain a film having a high photocatalytic activity and excellent abrasion resistance by sputtering a metallic target contg. Ti by using a gaseous mixture of oxygen and a specified ratio of helium as atmospheric gas.

The content of helium is controlled to 20 to 90 vol.% to the total of oxygen and helium. Making electric power to the target is controlled to 0.1 to 5.0 W/cm2. Moreover, the pressure of the atmospheric gas is preferably controlled to ≥1 m Torr. As the geometrical film thickness of the titanium oxide film, 5 to 1000 nm is suitable. Desirably, substrate heating is executed at 100 to 650°C heating temp. in the process of the film formation or the titanium film is subjected to post-heating in the air or in an atmosphere contg. oxygen after the film formation. The space between the glass substrate and the titanium oxide film may be provided with a functional film such as a metallic oxide film, a metallic nitride film, a metallic carbide film or the like. In the case of the substrate heating or the post-heating after the film formation, as a functional film, a silica film is provided to prevent the diffusion of sodium in glass into the titanium oxide film.