NOVELTY - A bipolar secondary battery comprises: a set of bipolar electrodes stacked in a stacking direction; electrolyte layers (17) disposed between the first active material layer and the second active material layer of immediately-adjacent pairs of bipolar electrodes of the set of bipolar electrodes; and seal members disposed between the current collectors (11) of the immediately-adjacent pairs of bipolar electrodes and about an outer periphery in order to prevent leakage of an electrolyte solution of the electrolyte layers.    USE - The bipolar secondary battery is useful for vehicles (claimed).    ADVANTAGE - The bipolar secondary battery has high power, reliable, efficient and has increased durability.    DETAILED DESCRIPTION - A bipolar secondary battery comprises: a set of bipolar electrodes stacked in a stacking direction, each bipolar electrode including a current collector with a first active material layer formed on a first surface of the current collector and the first active material layer having outer edges, and a second active material layer formed on a second surface of the current collector opposite the first surface and the second active material layer having outer edges; electrolyte layers disposed between the first active material layer and the second active material layer of immediately-adjacent pairs of bipolar electrodes of the set of bipolar electrodes; and seal members disposed between the current collectors of the immediately-adjacent pairs of bipolar electrodes and about an outer periphery in order to prevent leakage of an electrolyte solution of the electrolyte layers; where the outer edges of the first active material layers are positioned further from a center of the battery in a planar direction than the outer edges of the second active material layers, the planar direction being perpendicular to the stacking direction of the set of bipolar electrodes; and where each of the seal members has an edge portion overlapping the outer edges of the first active material layer in the stacking direction with the current collector provided between it. INDEPENDENT CLAIMS are:    (1) an assembled battery comprising a set of the bipolar secondary batteries, the bipolar secondary batteries being electrically connected to each other; and    (2) a vehicle comprising the bipolar secondary battery or the assembled battery as a motor driving power supply.    DESCRIPTION OF DRAWING(S) - The drawing shows a partial cross-sectional view of an arrangement of seal members of a bipolar secondary battery.    Current collector (11)    Positive-electrode active material layer (13)    Negative-electrode active material layer (15)    Electrolyte layers (17)    Seal portion (31)