Provided is a battery pack for a vehicle including an approximately rectangular pack case, a plurality of flat box-shaped battery modules, a cooling unit, and a junction box for storing a relay, in which: the plurality of battery modules is piled up flat in the pack case so that a terminal provided on a short side of each battery module is directed in a longitudinal direction of the pack case; the cooling unit is disposed at one end of the pack case in the longitudinal direction and configured to send and circulate cooling air in the pack case along an outer periphery of the pack case; and the junction box is disposed in a most downstream side of the circulating cooling air beside the cooling unit in a width direction of the pack case.