This invention provides a photoreactive composition in which reaction of a hydrolyzable metal compound takes place by irradiation of light.A photoreactive composition, which comprises a hydrolyzable metal compound (A) comprising a metal atom and a hydrolyzable functional group bonded to the metal atom and, a compound (B) promoting reaction, polymerization or crosslinking of the compound (A) in the presence of oxygen by irradiation of light.