Disclosed is a fluororesin-coated polymer film for reinforcing a polymer electrolyte membrane, wherein the fluororesin-coated polymer film is fabricated by forming on at least one side of a polymer film a coating of a reaction product of (A) a fluorine-containing copolymer composed of a fluoroolefin, a cyclohexyl group-containing acrylic ester, and a hydroxyl group-containing vinyl ether, and (B) a crosslinking agent having two or more isocyanate groups. The polymer film according to the present invention not only exhibits sufficiently high initial adhesion strength, with respect to the polymer electrolyte membrane, but also retains thereafter high adhesion strength in actual operating environments.