A secondary battery comprising: a cylindrical can having an upper end opening; an electrode assembly received in the cylindrical can and having an electrode tab ; and a cap assembly for sealing the upper end opening of the cylindrical can , wherein the cap assembly includes: a circular-plate-shaped safety plate ; and a cap-up disposed on the upper portion of the safety plate and surrounding the edge portion of the safety plate , and the electrode tab is in contact with and coupled to the cap-up , characterised in that the cap-up comprises: a terminal portion in the shape of a flat circular plate; a connection portion that is bent downwardly from an edge of the terminal portion ; a first extension portion that extends outwardly from a lower end of the connection portion in the horizontal direction; a bent portion that is bent downwardly from an edge of the first extension portion ; and a second extension portion that extends inwardly from a lower end of the bent portion in the horizontal direction. a cylindrical can having an upper end opening; an electrode assembly received in the cylindrical can and having an electrode tab ; and a cap assembly for sealing the upper end opening of the cylindrical can , wherein the cap assembly includes: a circular-plate-shaped safety plate ; and a cap-up disposed on the upper portion of the safety plate and surrounding the edge portion of the safety plate , and the electrode tab is in contact with and coupled to the cap-up , characterised in that the cap-up comprises: a terminal portion in the shape of a flat circular plate; a connection portion that is bent downwardly from an edge of the terminal portion ; a first extension portion that extends outwardly from a lower end of the connection portion in the horizontal direction; a bent portion that is bent downwardly from an edge of the first extension portion ; and a second extension portion that extends inwardly from a lower end of the bent portion in the horizontal direction. a circular-plate-shaped safety plate ; and a cap-up disposed on the upper portion of the safety plate and surrounding the edge portion of the safety plate , and the electrode tab is in contact with and coupled to the cap-up , characterised in that the cap-up comprises: a terminal portion in the shape of a flat circular plate; a connection portion that is bent downwardly from an edge of the terminal portion ; a first extension portion that extends outwardly from a lower end of the connection portion in the horizontal direction; a bent portion that is bent downwardly from an edge of the first extension portion ; and a second extension portion that extends inwardly from a lower end of the bent portion in the horizontal direction. a terminal portion in the shape of a flat circular plate; a connection portion that is bent downwardly from an edge of the terminal portion ; a first extension portion that extends outwardly from a lower end of the connection portion in the horizontal direction; a bent portion that is bent downwardly from an edge of the first extension portion ; and a second extension portion that extends inwardly from a lower end of the bent portion in the horizontal direction. <EOS>