Disclosed is a film having high gas barrier properties immediately after it is produced. The film has higher gas barrier properties than the conventional films, and can be produced at low cost by a process having the minimum steps. The gas barrier film is obtained by forming an inorganic thin film on at least one side of a thermoplastic polymer film and applying a solution over the organic thin film side, which solution contains at least one kind of low molecular weight electrolyte ions having a molecular weight of not more than 1000 and selected from the group consisting of alkali metal ions, alkaline earth metal ions and ammonium ions. The total concentration of ions in the solution is not less than 1 x 10-5 mol/L and less than 10 mol/L, and also less than the saturated solution concentration.