Case for secondary battery and secondary battery including the same

A secondary battery comprising:

• an electrode assembly comprising a first electrode, a second electrode, and a separator positioned between the first electrode and the second electrode;
• and
• a case configured to accommodate the electrode assembly, the case comprising:
• a first case comprising a first body portion and a first fastening portion, the first fastening portion positioned at one end of the first body portion;
• a second case comprising a second body portion, a second fastening portion, the second fastening portion positioned at one end of the second body portion and configured to be coupled to the first fastening portion of the first case, and a third fastening portion, the third fastening portion positioned at an opposite end of the second body portion;
• and
• a third case comprising a third body portion and a fourth fastening portion, the fourth fastening portion formed at one end of the third body portion and configured to be coupled to the third fastening portion of the second case.