BATTERY MODULE ASSEMBLY HAVING IMPROVED RELIABILITY,AND MEDIUM AND LARGE-SIZED BATTERY PACK INCLUDING SAME

Disclosed herein is a battery module assembly having one or more plate-shaped battery cells, including two or more battery modules having cell units, each of which includes one or more battery cells, electrically connected to one another, a pair of an upper case and a lower case to surround outer circumferences of the battery modules such that one surface of each of the outermost battery modules is exposed outside in a state in which the battery modules are erected on their sides, one or more first fastening holes vertically formed at a top of the upper case and a bottom of the lower case in a direction in which first fastening holes face each other to fasten and fix the upper case and the lower case, and two or more second fastening holes horizontally formed at a front and/or a rear of the upper case and a front and/or a rear of the lower case to position or fix the battery module assembly.