A secondary battery including: an electrode assembly; a case accommodating the electrode assembly; and a cap assembly coupled to the case. The cap assembly includes: a cap-up exposed at a top of the cap assembly; a safety vent under the cap-up; and a reinforcement plate between the cap-up and the safety vent and extending along a periphery of the cap-up. The safety vent includes a protrusion protruding toward the electrode assembly and is electrically connected to the electrode assembly via the protrusion.