A non-aqueous electrolyte secondary battery with improved cycle durability includes a power generating element including a positive electrode obtained by forming a positive electrode active material layer containing a positive electrode active material on a surface of a positive electrode current collector, a negative electrode obtained by forming a negative electrode active material layer containing a negative electrode active material on a surface of a negative electrode current collector, and a separator, a ratio of a rated capacity to a pore volume of the separator being 1.55 Ah/cc or more, a ratio of a battery area to a rated capacity being 4.0 cm2/Ah or more, and a rated capacity being 30 Ah or more, wherein a variation in porosity in the separator is 4.0% or less.