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, the electrode lead comprising: an outer protrusion protruding to the outside of the outer case; an inner connection part disposed in the outer case; 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, the notch part being disposed in a direction crossing a direction that is directed from the electrode assembly toward the outer protrusion, the inner connection part comprising: 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 integrally connected to the outer protrusion, wherein the inner connection part is bent by using the notch part as an axis so that the tab bonding area and the tab non-bonding area face each other, characterized in that the notch part comprises a first notch part and a second notch part, which are spaced apart from each other, and the inner connection part is bent by using the first notch part and the second notch part as axes, the first notch part is disposed relatively close to the electrode assembly when compared to the second notch part, and the first notch part has a thickness less than that of the second notch part or the second notch part has a thickness less than that of the first notch part. an electrode assembly comprising an electrode tab; an outer case accommodating the electrode assembly; and an electrode lead electrically connected to the electrode tab, the electrode lead comprising: an outer protrusion protruding to the outside of the outer case; an inner connection part disposed in the outer case; 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, an outer protrusion protruding to the outside of the outer case; an inner connection part disposed in the outer case; 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, the notch part being disposed in a direction crossing a direction that is directed from the electrode assembly toward the outer protrusion, the inner connection part comprising: 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 integrally connected to the outer protrusion, 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 integrally connected to the outer protrusion, wherein the inner connection part is bent by using the notch part as an axis so that the tab bonding area and the tab non-bonding area face each other, characterized in that the notch part comprises a first notch part and a second notch part, which are spaced apart from each other, and the inner connection part is bent by using the first notch part and the second notch part as axes, the first notch part is disposed relatively close to the electrode assembly when compared to the second notch part, and the first notch part has a thickness less than that of the second notch part or the second notch part has a thickness less than that of the first notch part.