A thin film comprising titanium oxide as its main component, wherein the thin film includes titanium, oxygen and copper, content of Ti is 29.0 at % or higher and 34.0 at % or less and content of Cu is 0.003 at % or higher and 7.7 at % or less with remainder being oxygen and unavoidable impurities, and ratio of oxygen component to metal components, O/(2Ti+0.5Cu), is 0.96 or higher. This invention aims to obtain a thin film comprising titanium oxide as its main component with a high refractive index and low extinction coefficient and a sintered compact sputtering target comprising titanium oxide as its main component which is suitable for producing the foregoing thin film, to obtain a thin film with superior transmittance and low reflectance and which is effective as an interference film or protective film of an optical information recording medium, and to obtain a thin film that can be applied to a glass substrate; that is, a thin film that can be used as a heat ray reflective film, antireflection film, and interference filter.