A gas barrier film is provided comprising a base film of polyester provided, on at least one of its surfaces, with a deposited layer of an inorganic compound and a gas barrier layer of a copolymer resin composition formed on the former. The gas barrier layer is produced from a mixture of a base material composed at least of the two components of (a) an unsaturated nitrile that accounts for 10% to 30% by mass of the copolymer and (b) an unsaturated compound with a hydroxyl group that accounts for 30% to 70% by mass of the copolymer; (c) a curing agent that contains a compound with an isocyanate group; and (d) a compound that has either two or more carboxylic acid groups or one or more carboxylic anhydride groups.