Positive and negative electrode plates are respectively joined to positive and negative electrode terminals through leads. At least one of the leads joined to the positive or negative electrode plate is made of a stack of first and second metal layers. The first metal layer has a resistance higher than that of the second metal layer. The second metal layer has a melting point lower than that of the first metal layer. When a short-circuit current flows in the secondary battery, current is concentrated in the second metal layer to cause a blowout of the second metal layer, and then, an increase in an heat generation amount due to an increase in a current density of a short-circuit current flowing in the first metal layer causes a blowout of the first metal layer, thereby causing a blowout of the lead to interrupt the short-circuit current.