A battery pack includes battery stacks each formed of battery cells stacked on one another and bus bars disposed at a first end side of the battery stack for connection between electrode terminals of the battery cells, a battery pack case housing the battery stacks, a fan device disposed inside the battery pack case for circulating fluid within the battery pack case and a spacer disposed between respective adjacent battery cells to guide the fluid to flow in a direction from the first end side to a second end side opposite to the first end side along lateral sides of the battery cells. Each of the battery cells includes a battery cell case as an outer shell thereof that includes an exposed portion having a predetermined exposed length by which the battery cell case projects from an end at the first end side of the spacer.