A power supply device disposes an end plate at each end of a battery stack in a stacked direction of the battery stack, and couples a binding bar to the end plate, so as to fix battery cells. The binding bar includes a plate-shaped bar that extends in the stacked direction of the battery stack, and an engagement block that is fixed to the plate-shaped bar and protrudes as a face opposing an outer peripheral face of the end plate. The End plate includes a fitting part to which the engagement block is guided, and a stopper. The fitting part is disposed on the outer peripheral face of the end plate. The stopper is disposed closer to the battery stack with respect to the fitting part, and abuts the engagement block.