Disclosed herein is a battery pack including (a) a battery module assembly arranged in a lateral direction, (b) a pair of a front support member and a rear support member to cover the front and rear of outermost battery modules of the battery module assembly, (c) at least one upper end connection member to connect the front support member and the rear support member to each other at the upper end of the battery module assembly, and (d) at least one lower end connection member to connect the front support member and the rear support member to each other at the lower end of the battery module assembly, wherein the cartridge is provided at the lower end thereof with a fastening hole, via which the at least one lower end connection member is mounted.