A secondary battery includes an electrode assembly; a case accommodating the electrode assembly; a cap plate sealing the case and having an inversion plate; and an insulation plate having a short-circuit hole generally corresponding to the inversion plate and an air opening spaced from the short-circuit hole and fluidly connected to a top surface of the cap plate; a terminal plate coupled to a top surface of the insulation plate and electrically connected to the electrode assembly; and a terminal assembly including a sealing member coupled to a bottom surface of the insulation plate and formed to encompass the short-circuit hole and the air opening.