The present disclosure relates to a secondary battery. The secondary battery includes a first case having a hexahedral shape, a second case having a hexahedral shape, and coupled to the first case, an electrode assembly in the first case and the second case, a pair of current collector plates electrically connected to the electrode assembly, and electrically connected to the first case and the second case, respectively, and a sealing member including an insulating material between the first case and the second case.