A packaging material for lithium-ion battery comprises a substrate layer made of a plastic film, and a first adhesive layer, a metal foil layer, an anti-corrosion layer, a second adhesive layer and a sealant layer successively laminated on one surface of the substrate layer. The plastic film has a water absorption rate of not less than about 01% to not larger than about 3% when determined by a method described in JIS K 7209:2000 and when the plastic film is subjected to a tensile test (wherein the sample of the plastic film is stored for 24 hours in an environment of 23° C. and 40% R.H., and subjected to a tensile test in the same environment as indicated above under conditions of a sample width of 6 mm, a gauge length of 35 mm and a tensile speed of 300 mm/minute), stress values in an MD direction of the sample and in a TD direction of the sample after stretching by about 10% relative to a length of the sample prior to the tensile test are both from not larger than about 110 MPa and at least one of the stress values in the MD direction of the sample and in the TD direction of the sample is not less than about 70 MPa.