To provide a gas barrier film having superior gas barrier properties to oxygen and water vapor, etc., and capable of maintaining the superior gas barrier properties over the long period of time.

The hydrolysate is obtained by mixing the alkoxysilane (A) that has tow or more alkoxy groups and one or more radical polymerization group in a molecule, and water, wherein the silanol group is formed by hydrolysis reaction of the alkoxy group. The composition for coating is obtained by adding to this hydrolysate, the urethane (meta) acrylate (B) and the multifunction (meta) acrylate (C) that has no urethane bond in the molecule. The gas barrier resin layer that is formed by doing dehydrating condensation reaction of the silanol group that the hydrolysate has, after the radical polymerization is done or while doing, is laminated and integrated on the synthetic resin film by irradiating this composition for coating with the active energy ray, in the gas barrier film.