PURPOSE: To improve an interlayer adhesive force, by bringing an ethylene-vinyl acetate copolymer saponified layer into contact with other thermoplastic resin layer in a die for a longer period of time than specified.

CONSTITUTION: An ethylene-vinyl acetate copolymer saponified substance (X)- layer, comprising ethylene whose containing amount ranges from 15W55mol% and vinyl acetate component whose saponifying degree is 90mol% or more, and a layer of an other thermoplastic resin (Y) than X are inflation-molded, by such a method as joins them together in a die, to produce a multi-layer film. When producing the multi-layer film in the manner described above, the layer X and layer Y being in a melted condition are adhered to each other by the pressure in a die for a period of 2.0 seconds, preferably 2.2W5.0 seconds. Said condition can be fulfilled by increasing a rand length and reducing an exhaust volume. The constitution of the multi- layer film is not limited to a structure of 2 layers of the X and Y. If the constitution is such that at least one layer each of the layer X and layer Y is contained therein, the multi-layer can optionally be constituted.