A rechargeable battery including an electrode assembly, a case, a cap assembly, and a core. The electrode assembly includes an anode, a cathode, and a separator interposed between the anode and the cathode. The case has a space for housing the electrode assembly. The cap assembly is connected to the case and electrically connected to the electrode assembly. The core is disposed inside the electrode assembly, and has a distance between the exterior and the center thereof at one end in a length direction that is greater than a distance between the exterior and the center thereof at the center in the length direction.