There is provided a secondary battery enabling an electrode terminal to be deformed in an internal direction of a can by preventing the upper plate of the can from being deformed in an internal direction of the can when a compression is applied in a direction perpendicular to the longitudinal axis. In one embodiment, a secondary battery includes a can having one opened portion to accommodate an electrode assembly. An upper plate is positioned at the opened portion of the can and has a pair of short side portions and a pair of long side portions connected both sides of the short side portions. In the secondary battery, a short circuit preventing portion formed thinner than other regions while crossing between the long side portions is further formed at a central portion of the bottom surface of the upper plate. Accordingly, the stability of the secondary battery can be improved.