A rechargeable battery includes an electrode group in a case, the electrode group including a first electrode and a second electrode, a cap plate coupled to the case, an electrode terminal electrically connected to the first electrode, the electrode terminal being electrically insulated from the cap plate, and a current interrupt device (CID) electrically connected to the second electrode and the cap plate, the CID including a membrane on a first surface of the cap plate, the membrane being between and electrically connecting the second electrode and the cap plate, and the membrane being configured to interrupt the electrical connection when a voltage greater than a setting voltage is charged, a first insulator contacting the first surface of the cap plate and at least one surface of the membrane to support the membrane, and a fastening member connecting the cap plate and the first insulator.