A non-aqueous secondary battery having an electrode group and a non-aqueous electrolytic solution, characterized in that: (1) the electrode group is contained in a casing made of a sheet having a resin layer with a thickness of 0.5 mm or less, (2) the non-aqueous solvent contains -butyrolactone, ethylene carbonate, at least one vinylene carbonate compound and at least one vinylethylene carbonate compound, (3) the amounts of the vinylene carbonate compound, the vinylethylene carbonate compound and sum total of both are, respectively, 0.01 to 5% by weight, 0.01 to 5% by weight and 0.02 to 6% by weight, based on the total weight of the non-aqueous solvent, and (4) the amounts of the -butyrolactone and the ethylene carbonate are, respectively, 50% by volume or more and 10% by volume or more, based on the total volume of the non-aqueous solvent.