Disclosed herein is a middle- or large-sized battery module comprising: a battery cell stack including a plurality of battery cells or unit modules electrically connected with each other; a first module case constructed in a structure to entirely surround one side end of the battery cell stack and to partially surround the upper and lower ends of the battery cell stack; a second module case coupled with the first module case, the second module case being constructed in a structure to entirely surround the other side end of the battery cell stack and to partially surround the upper and lower ends of the battery cell stack; a sensing member mounted to the first module case or the second module case; and a battery management system (BMS) mounted to the first module case or the second module case.