A battery module assembly comprising: two or more battery modules having cell units, each of which comprises one or more battery cells having insulating tape at least partially attached to an outer circumference thereof excluding electrode terminals thereof, electrically connected to one another; a pair of an upper case and a lower case to surround an upper part and a lower part of the battery modules in a state in which the battery modules are erected on their sides; a bus bar assembly disposed at a front of the battery modules to electrically connect the battery modules to one another; and fastening holes formed at a top of the upper case and a bottom of the lower case to position or fix the battery module assembly, characterized in that the bus bar assembly comprises: (a) a cover plate formed of an electrically insulative material, the cover plate being fixed to the front of the battery modules, the cover plate comprising a pair of body parts; and (b) the pair of body parts, each of which is configured to have a structure in which an external input and output terminal is formed at an L-shaped side thereof and two or more bus bars diverge from the other side thereof in a state in which the body parts are mounted on the cover plate, and the body parts are arranged so as to face each other in a direction horizontal to a direction in which the battery modules are arranged. two or more battery modules having cell units, each of which comprises one or more battery cells having insulating tape at least partially attached to an outer circumference thereof excluding electrode terminals thereof, electrically connected to one another; a pair of an upper case and a lower case to surround an upper part and a lower part of the battery modules in a state in which the battery modules are erected on their sides; a bus bar assembly disposed at a front of the battery modules to electrically connect the battery modules to one another; and fastening holes formed at a top of the upper case and a bottom of the lower case to position or fix the battery module assembly, characterized in that the bus bar assembly comprises: (a) a cover plate formed of an electrically insulative material, the cover plate being fixed to the front of the battery modules, the cover plate comprising a pair of body parts; and (b) the pair of body parts, each of which is configured to have a structure in which an external input and output terminal is formed at an L-shaped side thereof and two or more bus bars diverge from the other side thereof in a state in which the body parts are mounted on the cover plate, and (a) a cover plate formed of an electrically insulative material, the cover plate being fixed to the front of the battery modules, the cover plate comprising a pair of body parts; and (b) the pair of body parts, each of which is configured to have a structure in which an external input and output terminal is formed at an L-shaped side thereof and two or more bus bars diverge from the other side thereof in a state in which the body parts are mounted on the cover plate, and the body parts are arranged so as to face each other in a direction horizontal to a direction in which the battery modules are arranged.