A battery with improved safety that can more surely short-circuit electrodes when flattened out by the external force is provided. A center pin (30) is inserted in the center of a spirally wound electrode body formed by layering and spirally winding a cathode and an anode with a separator in between. The center pin (30) has a cut line (31) provided in the longitudinal direction and a first cutout (32) vertically crossing the cut line (31). When flattened out by the external force, a corner (33) at an intersection of the cut line (31) and the first cutout (32) is projected, and short-circuit is surely generated. Further, it is preferable that the center pin (30) has a second cutout (34) in the direction perpendicular to the cut line (31) in a position facing the cut line (31) in the circumferential direction. It is also preferable that the center pin (30) has a cross sectional shape of an oval or an ellipse, and the cut line (31) is provided in a position where the diameter of the oval or the ellipse is the largest.