To provide a method for recovering aluminum foil in a metallic state without oxidizing the aluminum foil from a composite film which is formed by laminating the aluminum foil and a resin.

In the method for recovering the aluminum foil, the composite film formed by laminating the aluminum foil and the resin is treated in a subcritical condition and/or in a supercritical condition under coexistence of water, is separated and the aluminum foil is recovered in the metallic state. When treating the composite film in the subcritical condition and/or in the supercritical condition, the composite film and water are housed in a vessel and non-oxidizing gas is made to bubble into the water to purge oxygen in water and the vessel before treatment in the subcritical condition and/or in the supercritical condition.