NOVELTY - A biaxially-stretched nylon film, which is an easily adhesive nylon film, obtained by heat-processing non-expanded or expanded nylon film coated with polyurethane resin or acrylic acid copolymer resin, and a crosslinking agent. The nylon film is coated before heat-processing. The nylon film has maximum heat shrinkage stress of 5 MPa or less at 170-210 degrees C in machine direction and transverse direction.    USE - Biaxially-stretched nylon film is used as main base material of wrapping materials for cases of batteries (claimed) e.g. lithium ion secondary battery and lithium ion polymer battery. Uses include but are limited to fuel cell, electrolysis type capacitor, liquid capacitor, solid capacitor and double layered capacitor used for personal computer, portable terminal devices, video camera, electric vehicle, storage battery for energy storage, robot and satellite.    ADVANTAGE - The biaxially-stretched nylon film has excellent tensile strength. The occurrence of de-lamination between the barrier layer and base material layer at high temperature and humidity, and fracture of aluminum foil and pinhole, are suppressed.    DETAILED DESCRIPTION - A biaxially-stretched nylon film, which is an easily adhesive nylon film, obtained by heat-processing non-expanded or expanded nylon film coated with polyurethane resin or acrylic acid copolymer resin, and a crosslinking agent. The nylon film is coated before heat-processing. The nylon film has maximum heat shrinkage stress of 5 MPa or less at 170-210 degrees C in machine direction and transverse direction. The breaking strength of sample having width of 15 mm, measured by uniaxial tension test with distance between zippers of 100 mm and tensile velocity of 200 mm/minute at 0 degrees in machine direction, at 45 degrees , 90 degrees in transverse direction and 135 degrees , is 240 MPa or more. An INDEPENDENT CLAIM is included for battery case wrapping material comprising base material layer, barrier layer and sealant layer. The base material layer of battery case wrapping material is printed on coating surface of nylon film, which is provided on barrier layer.