Provided is an energy storage device which includes an electrode assembly in which electrode plates are stacked; and a current collector connected to an end portion of the electrode assembly, wherein the end portion of the electrode assembly includes: an electrode plate welded portion at which the stacked electrode plates are welded to each other in a stacking direction and not joined to the current collector; and a current collector joined portion which is joined to the current collector and is arranged adjacently to the electrode plate welded portion in a current collector extending direction that intersects with the stacking direction.