A secondary battery comprising: an electrode assembly comprising an electrode tab ; an outer case accommodating the electrode assembly ; and an electrode lead electrically connected to the electrode tab , wherein the electrode lead comprises: an outer protrusion protruding to the outside of the outer case ; an inner connection part disposed in the outer case ; an insulation part disposed between the outer protrusion part and the inner connection part; and a notch part disposed on the inner connection part and having a relatively thin thickness when compared to that of the other area of the electrode lead , wherein the notch part is disposed from the electrode assembly toward the outer protrusion , the inner connection part comprises: a tab bonding area disposed on one side of the notch part and bonded to the electrode tab ; and a tab non-bonding area disposed on the other side of the notch part and connected to the insulation part , wherein the tab bonding area and the tab non-bonding area are bent by using the notch part as an axis to face each other, the electrode lead has the shape of an L-letter in the alphabet when the inner connection part is unfolded by using the notch part as an axis, the notch part has the same length as the width (w) of the inner connection part , and at least a portion of the electrode tab is disposed between the tab bonding area and the tab non-bonding area . an electrode assembly comprising an electrode tab ; an outer case accommodating the electrode assembly ; and an electrode lead electrically connected to the electrode tab , wherein the electrode lead comprises: an outer protrusion protruding to the outside of the outer case ; an inner connection part disposed in the outer case ; an insulation part disposed between the outer protrusion part and the inner connection part; and a notch part disposed on the inner connection part and having a relatively thin thickness when compared to that of the other area of the electrode lead , wherein the notch part is disposed from the electrode assembly toward the outer protrusion , the inner connection part comprises: an outer protrusion protruding to the outside of the outer case ; an inner connection part disposed in the outer case ; an insulation part disposed between the outer protrusion part and the inner connection part; and a notch part disposed on the inner connection part and having a relatively thin thickness when compared to that of the other area of the electrode lead , wherein the notch part is disposed from the electrode assembly toward the outer protrusion , the inner connection part comprises: a tab bonding area disposed on one side of the notch part and bonded to the electrode tab ; and a tab non-bonding area disposed on the other side of the notch part and connected to the insulation part , wherein the tab bonding area and the tab non-bonding area are bent by using the notch part as an axis to face each other, the electrode lead has the shape of an L-letter in the alphabet when the inner connection part is unfolded by using the notch part as an axis, the notch part has the same length as the width (w) of the inner connection part , and at least a portion of the electrode tab is disposed between the tab bonding area and the tab non-bonding area . <EOS>