The gas barrier film having a thermoplastic polymer film, and an inorganic thin film provided on at least one surface of the thermoplastic polymer film, which gas barrier film is formed by applying, to the inorganic thin film, a solution which contains at least one ion species selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions and originating from a low-molecular-weight electrolyte having a molecular weight of 1,000 or less and which has a total ion concentration of the ion species of 1.times.10.sup.-5 mol/L or more and less than 10 mol/L and a solution concentration less than a saturation concentration.