To provide a secondary battery capable of realizing large discharge volume, as well as with an initial discharge volume and charge/discharge cycle characteristics improved for restraining damages of an electrode structure by reconsidering a design of a conventional electrode size.

The secondary battery made of an electrode wound body of which an anode 1 and a cathode 2 of long shapes having long sides and short sides are wound in a short side (width) direction as a winding axis direction through a separator 3, is formed. At this time, when G is made as a width of the anode 1 after charging in a region not opposed to a forming region of a cathode active material layer 2b, D is made as a width of the cathode 2 after charging in a forming region of the cathode active material layer 2b, the relation between G and D is G-D≤1 mm, and when C is made as a width of the anode 1 after charging in a region opposed to a forming region of the cathode active material layer 2b, the relation between D and C is D≤C. In order to fulfill the latter requirement, in case of G is about a size of 31.5 mm suited for a specification size of the secondary battery, it is only necessary to fulfill the relation of -4 mm≤G-D.

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