A surface treatment agent, which contains: (A) a hydrolyzable metal
alkoxide or a hydrolyzate thereof, (B) a fluorocompound containing a
perfluoroalkyl group and a functional group reactive with the
hydrolyzable metal alkoxide (A), and (C) an adhesion improvement agent,
can provide a film having transparency and durability while maintaining
excellent soil releasability and low refractive index.