A rechargeable battery is disclosed. In one aspect, the battery includes an electrode assembly including a first electrode and a second electrode wound with a separator interposed between the first and second electrodes and a case accommodating the electrode assembly. The battery also includes a cap assembly including a cap plate coupled to the case to close an opening formed on one side of the case, a first terminal placed at the cap plate and electrically connected to the first electrode, and a second terminal placed at the cap plate and electrically connected to the second electrode. The case includes a concave portion formed on one outer surface.