The nonaqueous electrolyte secondary battery 100 according to the present invention is provided with a wound electrode assembly in which a positive electrode sheet and a negative electrode sheet are wound, with a porous separator sheet 30 interposed therebetween. A filler layer 40 comprising an inorganic filler and a binder is formed on one side of the separator sheet 30. The filler layer 40 is continuously provided from the winding start end 38A to the winding finish end 38B of the separator sheet 30 in the winding direction of this sheet. The separator sheet 30 has low porosity regions 36A, 36B, which have a lower porosity than a location 35 outside these regions, in regions having prescribed width WA, WB from the winding start end 38A and/or the winding finish end 38B of the sheet toward the center of the sheet.