A battery module including a unit cell assembly including two or more battery cells or unit modules; a left case coupled to a left side of the assembly, the left case provided at a left outer side thereof with a first fastening groove extending parallel to a longitudinal direction of the battery module such that a sensing assembly is fastened into the first groove, the left case being provided at opposite ends thereof with second fastening grooves formed parallel to a height direction of the battery; and a right case coupled to a right side of the assembly, an external input and output terminal oriented to a front of the battery, the right case provided at a right inner side thereof with a plurality of fixing grooves formed parallel to a longitudinal direction of the assembly such that the assembly is fastened and fixed into the fixing grooves is provided.