A power supply device comprising: a battery stack where a plurality of battery cells are stacked; a pair of end plates that are disposed at both end portions of the battery stack; and a bind bar that extends in a stacking direction of the plurality of battery cells of the battery stack and has both end portions coupled to the end plates, wherein the battery stack is a quadrangular prism extending in the stacking direction of the battery cells, and has four surrounding surfaces including an electrode surface where sealing plates of the plurality of battery cells are disposed on a same plane, a bottom surface on an opposite side of the electrode surface, and facing side surfaces where the bind bar is disposed, a vertical direction being defined from the electrode surface to the bottom surface, the bind bar is divided in the vertical direction and each of the divided bind bars includes a bent piece that is fixed and attached to a surface of one of the pair of end plates, characterized in that at least one of the divided bind bars further includes a bent piece fixed with a single bolt, the bent piece being fixed to the one of the pair of end plates via one bolt, the one of the pair of end plates includes a stopper wall where an outer peripheral edge of the bent piece fixed with the single bolt is fitted to prevent rotation, the bent piece fixed with the single bolt is in contact with the stopper wall to be fixed to the pair of one of the end plates in a state where the rotation is prevented, wherein the one of the pair of end plates has an upper edge of the stopper wall formed as a planar projecting surface, the stopper protrusion of the bind bar includes: a cover plate that is disposed on the projecting surface of the stopper wall of the one of the pair of end plates; and a peripheral wall portion that couples an outer peripheral edge of the cover plate to the fixing portion, the cover plate is disposed on the projecting surface of the stopper wall, and the peripheral wall portion is in contact with the stopper wall to prevent the rotation of the bind bar. a battery stack where a plurality of battery cells are stacked; a pair of end plates that are disposed at both end portions of the battery stack; and a bind bar that extends in a stacking direction of the plurality of battery cells of the battery stack and has both end portions coupled to the end plates, wherein the battery stack is a quadrangular prism extending in the stacking direction of the battery cells, and has four surrounding surfaces including an electrode surface where sealing plates of the plurality of battery cells are disposed on a same plane, a bottom surface on an opposite side of the electrode surface, and facing side surfaces where the bind bar is disposed, a vertical direction being defined from the electrode surface to the bottom surface, the bind bar is divided in the vertical direction and each of the divided bind bars includes a bent piece that is fixed and attached to a surface of one of the pair of end plates, characterized in that at least one of the divided bind bars further includes a bent piece fixed with a single bolt, the bent piece being fixed to the one of the pair of end plates via one bolt, the one of the pair of end plates includes a stopper wall where an outer peripheral edge of the bent piece fixed with the single bolt is fitted to prevent rotation, the bent piece fixed with the single bolt is in contact with the stopper wall to be fixed to the pair of one of the end plates in a state where the rotation is prevented, wherein the one of the pair of end plates has an upper edge of the stopper wall formed as a planar projecting surface, the stopper protrusion of the bind bar includes: a cover plate that is disposed on the projecting surface of the stopper wall of the one of the pair of end plates; and a peripheral wall portion that couples an outer peripheral edge of the cover plate to the fixing portion, a cover plate that is disposed on the projecting surface of the stopper wall of the one of the pair of end plates; and a peripheral wall portion that couples an outer peripheral edge of the cover plate to the fixing portion, the cover plate is disposed on the projecting surface of the stopper wall, and the peripheral wall portion is in contact with the stopper wall to prevent the rotation of the bind bar.