To provide a coating-film-forming composition for a photocatalyst which can be easily applied and strongly bonded to a substrate surface without the necessity for high-temperature heat treatment, can be prepared in a neutral region, and has a high titanium oxide concentration; and a coating film and a coated article for a photocatalyst both excellent in photocatalytic activity.

This composition is prepared by homogeneously dispersing a titanium oxide powder in a peroxotitanic-acid-containing dispersion medium and is used for preparing a coating film and a coated article for a photocatalyst.