A battery pack comprises a pair of support members (35), battery modules (3, 5, 7) arranged between the support members (35), and stacking members (43) for bridging between the support members (35) to support the battery modules (3, 5, 7). An end of each stacking member (43) is extended to form an extended section (43a) which protrudes from the battery modules (3, 5, 7). Auxiliary equipment (12) is mounted to the battery modules to the side surface thereof which is one of the surfaces having provided thereto the pair of support members (35) and on which the extended sections (43a) of the stacking members (43) are provided.