NOVELTY - A composite multilayer film has a polyolefin type resin film (A) formed on one surface of aluminum layer (B) and a polyamide layer (C) on other surface of layer (B). Film (A) has a layer (A-2) of water-absorbing resin composition provided between acid-modified polyolefin resin layer (A-1) and crystalline polypropylene layer (A-3). The water-absorbing resin composition contains polyethylene type resin composition (100 mass parts) and water-absorptive fillers (5-200 mass parts). Polyethylene type resin composition contains ethylene polymer and acid-modified resin.    USE - Composite multilayer film for molded product used as cladding material of secondary battery (both claimed). Can also be use as packaging material for foodstuffs, (such as curry, confectionery and potato chips), shampoo, liquid detergent, and industrial chemicals such as methanol.    ADVANTAGE - The adhesive strength of aluminum foil and polyolefin film is improved. The multilayer film is excellent in damp-proof property and solvent resistance.    DETAILED DESCRIPTION - A composite multilayer film has a polyolefin type resin film (A) formed on one surface of aluminum layer (B) and a polyamide layer (C) on other surface of layer (B). The film (A) has a layer of water-absorbing resin composition provided between an acid-modified polyolefin resin layer and a crystalline polypropylene layer. The layer (B) is laminated on the water-absorbing resin layer. The water-absorbing resin composition contains polyethylene type resin composition (100 mass parts) and water-absorptive fillers (5-200 mass parts). The polyethylene type resin composition contains ethylene polymer (99-60 mass%) and acid-modified resin (1-40 mass%), such that the total content is 100 mass%. The ethylene polymer has peak top melting point of 110 degrees C or more at the highest-temperature side in differential scanning calorimetry (DSC) melting curve, heat of fusion of 90-180 J/g, crystallinity degree of 10-60% at 110 degrees C, and melt flow rate of 0.1-10 g/10 minutes at 190 degrees C and 21.18 N load. The filler contains particle diameter (D99) of 30 mu m or less and particle diameter (D50) of 20 mu m or less, where D50 and D99 are particle diameter providing a particle diameter accumulation in particle size distribution of 50 mass% and 99 mass%, respectively, from a small diameter side. A layer of polyester type resin (D) is further provided on layer (C).    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of composite multilayer film.    Polyolefin-type resin film (A)    Acid-modified polyolefin resin layer (A-1)    Water-absorbing-resin layer (A-2)    Crystalline polypropylene layer (A-3)    Aluminum layer (B)    Polyamide layer (C)    Polyester-type resin layer (D)