In a method for producing a gas barrier laminate film comprising the step of applying a mixture containing at least one kind of alkoxysilane, an acid catalyst and a hydrophilic resin to a polymer base film to form a coating layer, the acid catalyst is contained in the mixture in an amount of 0.3 to 5.0 molar equivalents with respect to 1 molar equivalent of the alkoxysilane. There are provided a gas barrier laminate film having superior gas barrier property and a method for producing it.