A non-aqueous electrolyte secondary battery comprises an electrode assembly and an electrolyte solution. The electrode assembly is a wound-type electrode assembly or a stack-type electrode assembly each of which comprises a positive electrode plate having an active material layer. To the non-aqueous electrolyte secondary battery, a restraining pressure of 0.5 MPa or more is applied in a stacking direction of the positive electrode plates. The electrolyte solution includes LiFSO 3 , and the electrolyte solution has an electrical conductivity of 0.86 S/m or more at 25°C.