A secondary battery includes a wound electrode assembly in which a positive electrode sheet, a negative electrode sheet and a separator are stacked and wound. The positive electrode sheet is provided with a long positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is disposed on the positive electrode current collector. The negative electrode sheet is provided with a long negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is disposed on the negative electrode current collector. The separator is interposed between the positive electrode sheet and the negative electrode sheet. The negative electrode current collector has a first active material layer-free region at one edge of the negative electrode current collector in a winding direction of an axis of the wound electrode assembly. The first active material layer-free region is a region where the negative electrode active material layer is not formed. The positive electrode current collector has a second active material layer-free region at one edge of the positive electrode current collector in a winding direction of an axis of the wound electrode assembly. The second active material layer-free region is a region where the positive electrode active material layer is not formed. The negative electrode current collector and the positive electrode current collector are disposed, with the first active material layer-free region and the second active material layer-free region being projected toward opposite sides in the winding direction of the axis of the wound electrode assembly. A width of the negative electrode active material layer is wider than a width of the positive electrode active material layer and a bacterial cellulose is disposed in at least a surface layer of the negative electrode active material layer that faces the second active material layer-free region.