The present invention relates to a battery pack including: a plurality of battery modules each including a plurality of battery cells, wherein at least one of the battery modules has a layer structure with the remaining battery modules based on the ground; a battery management system (BMS) mounted adjacent to the battery modules and monitoring and controlling operation of the battery modules; a battery disconnect unit (BDU) mounted adjacent to the battery modules and controlling electrical connection of the battery modules; a base plate having a structure in which the battery modules are mounted on an upper surface thereof and a lower end part thereof is fixed to an external device; and a pack cover surrounding the battery modules and coupled to an outer periphery of the base plate.