A secondary battery includes an electrode assembly having a separating plate interposed between an anode plate and a cathode plate. A container receives the electrode assembly together with an electrolyte. The container is electrically connected to one of the anode plate and the cathode plate. Also, the secondary battery includes a cap assembly having an electrode terminal electrically connected to one of an end of the anode plate and the cathode plate. The cap assembly is fixed to an opening of the container to seal the same. Also included is a safety device having a PTC (positive temperature coefficient) element contacting the container without an element interposed therebetween.