A lithium secondary battery includes a fixing unit in a terminal plate to fix the terminal plate to an electrode terminal to prevent the terminal plate from rotating when an electrode tap is welded to a cap assembly or when the cap assembly is assembled with an upper portion of a can. The lithium secondary battery includes an electrode assembly having a first electrode plate, a second electrode plate and a separator, a can for receiving the electrode assembly and an electrolyte, and a cap assembly having a cap plate, an insulating plate, a terminal plate and an electrode terminal and being assembled with an upper opening of the can in order to seal the can. The terminal plate includes a fixing unit to fix the terminal plate to the electrode terminal such that the terminal plate is prevented from rotating. The terminal plate has a terminal hole into which the electrode terminal is inserted, and the fixing unit includes at least one recess formed at a lower surface of the terminal plate and connected to the terminal hole.