Secondary Battery

The present disclosure relates to a secondary battery. The secondary battery includes: an electrode assembly configured to comprise a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode and wound therearound; a case configured to have an opening formed on one side thereof to accommodate the electrode assembly; and a cap assembly joined to the one side of the case to seal the opening of the case, and the case comprises a notch formed on a side portion of the case.