A bipolar secondary battery, comprising: a battery main body including one laminated body or a plurality of laminated bodies connected in series, the laminated body comprising a plurality of bipolar electrodes and electrolyte layers laminated alternately, the bipolar electrode comprising a plate-like current collector, a positive electrode active material layer arranged on one surface of the current collector and a negative electrode active material layer arranged on another surface of the current collector; a case for housing the battery main body; a positive electrode current collecting plate having one surface joined to an inner peripheral surface of the case and another surface joined to one end of the battery main body, the positive electrode current collecting plate extending to an outside of the case; and a negative electrode current collecting plate having one surface joined to the inner peripheral surface of the case and another surface joined to another end of the battery main body, the negative electrode current collecting plate extending to an outside of the case; characterized by a cutoff mechanism for cutting off an electrical connection between the positive electrode current collecting plate and the negative electrode current collecting plate by exerting a tensile load there-between in response to an expansion deformation of the case, wherein the case is formed of a sheet-like case member (103a, 103b) and comprises a folded portion formed by bending the case member (103a, 103b) in inward and outward directions of the case such that the case expands in a lamination direction of the cells according to a gas pressure increase in the case. a battery main body including one laminated body or a plurality of laminated bodies connected in series, the laminated body comprising a plurality of bipolar electrodes and electrolyte layers laminated alternately, the bipolar electrode comprising a plate-like current collector, a positive electrode active material layer arranged on one surface of the current collector and a negative electrode active material layer arranged on another surface of the current collector; a case for housing the battery main body; a positive electrode current collecting plate having one surface joined to an inner peripheral surface of the case and another surface joined to one end of the battery main body, the positive electrode current collecting plate extending to an outside of the case; and a negative electrode current collecting plate having one surface joined to the inner peripheral surface of the case and another surface joined to another end of the battery main body, the negative electrode current collecting plate extending to an outside of the case; characterized by a cutoff mechanism for cutting off an electrical connection between the positive electrode current collecting plate and the negative electrode current collecting plate by exerting a tensile load there-between in response to an expansion deformation of the case, wherein the case is formed of a sheet-like case member (103a, 103b) and comprises a folded portion formed by bending the case member (103a, 103b) in inward and outward directions of the case such that the case expands in a lamination direction of the cells according to a gas pressure increase in the case.