PROBLEM TO BE SOLVED: To provide a method for producing a polymer functional film that is excellent in durability even when the film thickness of the polymer functional film is thick.SOLUTION: The method for producing a polymer functional film comprises polymerizing and curing a composition including a monomer and a photopolymerization initiator. The film thickness of the polymer functional film is more than 500 μm and not more than 1,000 μm. At least one kind of monomers is a styrenic monomer or an acrylic amide monomer each having a quaternary ammonium group or a sulfo group or a salt thereof. The photopolymerization initiator uses a combination of at least one kind of (I-1) photopolymerization initiator having a maximum absorption wavelength of not less than 300 nm and less than 350 nm and at least one kind of (I-2) photopolymerization initiator having a maximum absorption wavelength of not less than 350 nm and not more than 420 nm.
