A rechargeable battery includes an electrode assembly; a case accommodating the electrode assembly; a cap plate coupled to an opening of the case; an electrode terminal connected to the electrode assembly and extending through a terminal hole of the cap plate; and a retainer having first ends contacting the case and located between the electrode assembly and the side wall to support the electrode assembly and the side wall, wherein a thickness of the retainer gradually decreases away from the first ends of the retainer.