A battery module assembly having unit modules , each of which is configured to have a structure in which unit cells are loaded on a cartridge in a state in which the unit cells are electrically connected to each other via busbars , the battery module assembly comprising: two or more sub-modules arranged in a lateral direction while being spaced apart from each other, each of the sub-modules comprising two or more unit modules that are stacked in a height direction from a ground; a battery management system (BMS) mounted in a space defined between the sub-modules , the BMS being provided at one side thereof with communication terminals ; a base plate on which the sub-modules and the BMS are loaded; side cover plates mounted at sides of the sub-modules ; a top cover plate loaded on top surfaces of the sub-modules , the top cover plate being coupled to the sub-modules and to the side cover plates by fastening; and a front cover plate mounted at fronts of the sub-modules , the front cover plate being coupled to the sub-modules , the base plate, and the side cover plates , the front cover plate being provided with through holes, through which the communication terminals are exposed, and wherein the cartridge is provided at opposite sides thereof with protrusions , each of which has a fastening hole , and cartridges are coupled to each other so as to constitute each of the sub-modules by inserting cartridge fastening members through the fastening holes , the BMS is configured to have a hexahedral structure, and the communication terminals are mounted to the front cover plate in a state of being exposed from the front cover plate and protrude from an upper end and a lower end of one surface of the hexahedral structure, and the sub-modules are connected to each other via a sub-module fastening member , the sub-module fastening member extends between the upper communication terminal and the lower communication terminal of the BMS , and one surface of the BMS at which the sub-module fastening member extends is depressed such that the sub-module fastening member is mounted in the depression. two or more sub-modules arranged in a lateral direction while being spaced apart from each other, each of the sub-modules comprising two or more unit modules that are stacked in a height direction from a ground; a battery management system (BMS) mounted in a space defined between the sub-modules , the BMS being provided at one side thereof with communication terminals ; a base plate on which the sub-modules and the BMS are loaded; side cover plates mounted at sides of the sub-modules ; a top cover plate loaded on top surfaces of the sub-modules , the top cover plate being coupled to the sub-modules and to the side cover plates by fastening; and a front cover plate mounted at fronts of the sub-modules , the front cover plate being coupled to the sub-modules , the base plate, and the side cover plates , the front cover plate being provided with through holes, through which the communication terminals are exposed, and wherein the cartridge is provided at opposite sides thereof with protrusions , each of which has a fastening hole , and cartridges are coupled to each other so as to constitute each of the sub-modules by inserting cartridge fastening members through the fastening holes , the BMS is configured to have a hexahedral structure, and the communication terminals are mounted to the front cover plate in a state of being exposed from the front cover plate and protrude from an upper end and a lower end of one surface of the hexahedral structure, and the sub-modules are connected to each other via a sub-module fastening member , the sub-module fastening member extends between the upper communication terminal and the lower communication terminal of the BMS , and one surface of the BMS at which the sub-module fastening member extends is depressed such that the sub-module fastening member is mounted in the depression. <EOS>