SECONDARY BATTERY

A secondary battery has a simplified structure of a terminal part to reduce the number of parts, and terminal parts can be directly connected without requiring a separate part (for example, a bus bar) for mutual electrical connection between a battery and another battery. A secondary battery comprises: an electrode assembly, a case for accommodating the electrode assembly; a cap plate coupled to the case; and a terminal part that is electrically connected to the electrode assembly and is extended to penetrate through the cap plate, wherein the terminal part comprises a first area having a first thickness that is electrically connected to the electrode assembly from the inside of the case, and a second area having a second thickness that is thicker than the first thickness and is electrically connected to the first area from the outer side of the case.