A secondary battery including an electrode assembly, the electrode assembly including a first electrode plate, a separator, and a second electrode plate; a collecting plate electrically connected to the electrode assembly; a case accommodating the electrode assembly and the collecting plate; a cap plate sealing the case; and an electrode terminal passing through the cap plate and electrically connected to the collecting plate, wherein the cap plate includes an injection inlet at a side thereof, the injection inlet includes a blocking member therein, and the blocking member and the injection inlet are covered with a stopper.