The secondary battery includes a case in which a positive electrode lead and a negative electrode lead are provided, wherein the case includes an external layer exposed to the outside, an insulation layer disposed in the case and insulated, a conductive layer stacked between the external layer and the insulation layer, made of a conductive material, and having one side coming into contact with the positive electrode lead and the other side coming into contact with the negative electrode lead, and a safety member disposed at a center of the conductive layer to prevent electricity from flowing through the conductive layer at a predetermined temperature or less and melted at the predetermined temperature or more to allow the electricity to flow through the conductive layer.