Disclosed herein is a battery module including (a) a battery cell stack including two or more battery cells or unit modules electrically connected to each other in a state in which the battery cells or unit modules are vertically stacked, (b) a first housing to cover the entirety of the end of one side of the battery cell stack and portions of the top and bottom of the battery cell stack and (c) a second housing to cover the entirety of the end of the other side of the battery cell stack and the remainder of the top and bottom of the battery cell stack, wherein the first housing and the second housing are provided with coupling holes formed to couple the first housing and the second housing to each other, the coupling holes being horizontal coupling holes, through which coupling members can be inserted in the lateral direction.