NOVELTY - A nonaqueous electrolyte secondary battery has battery device having a positive electrode (11), negative electrode (12), and nonaqueous electrolyte layer. The battery device is sealed in a film-state packaging component (30). Nonaqueous electrolyte layer includes lithium salt, nonaqueous solution, and a polymer compound. The lithium salt includes lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bistrifluoromethylsulfonyl imide and/or lithium nonafluorobutanesulfonate.    USE - Nonaqueous electrolyte secondary battery e.g. lithium secondary battery is used as power supply for portable electronic device.    ADVANTAGE - The nonaqueous electrolyte secondary battery has high capacity, shelf stability, and charging/discharging characteristics. In the secondary battery, by suppressing the concentration of the free acid, generation of gaseous hydride such as hydrogen fluoride gas and generation of gas by corrosion reaction in battery is suppressed, and expansion of battery is therefore prevented. The consumption of lithium due to reaction between free acid and lithium in battery system is suppressed, and increase in internal resistance due to generation of lithium fluoride is prevented.    DETAILED DESCRIPTION - A nonaqueous electrolyte secondary battery has a battery device having a positive electrode having a collector, on which a positive electrode active material layer containing a positive electrode material is formed, a negative electrode, and a nonaqueous electrolyte layer. The battery device is sealed in a film-state packaging component. The nonaqueous electrolyte layer includes lithium salt, nonaqueous solution, and a polymer compound. The lithium salt includes lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bistrifluoromethylsulfonyl imide and/or lithium nonafluorobutanesulfonate. The concentration of free acid in electrolyte layer is 60 ppm or less.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of nonaqueous electrolyte secondary battery.    Positive electrode (11)    Negative electrode (12)    Film-state packaging component (30)    Rectangular films (30a,30b)    Film made of polyolefin resin (31)