A battery module including plate-shaped battery cells (100a and 100b) having electrode terminals (120, 121) formed at the upper and lower ends thereof, wherein the battery module comprises: two battery cells constructed in a stacked structure in which the electrode terminals of the battery cells are connected in series with each other and the electrode terminal connections are bent such that the battery cells are stacked; and a pair of cell covers (211 and 212) for restraining the repetitive expansion and contraction change of the battery cells during the charge and discharge of the battery cells while protecting the battery cells, wherein the two cell covers (211 and 212) of said pair have an inside structure corresponding to the outer shape of the battery cell stack and are mounted on an outer surface of the battery cell stack having the two battery cells (100a and 100b) overlapping with each other, the two cell covers of said pair surrounding said outer surface excluding the connected electrode terminals (120, 121) of the battery cells and being coupled with each other; and wherein each cell cover (211, 212) has a longitudinal direction between upper and lower ends thereof and a width lateral direction between opposite sides thereof, each cell cover being provided at a main outer surface thereof with a plurality of linear protrusions which are spaced apart from each other in the width lateral direction of the same cell cover, the linear protrusions being located on the same said main outer surface, and wherein the cell covers (211 and 212) have the same shape and have coupling parts (221 and 222) constructed in a bent structure formed symmetrically with respect to a vertical section between the cell covers, such that the cell covers are engaged with each other by elastic coupling of the cell covers, which are pressed while in contact with each other such that the cell covers face each other. two battery cells constructed in a stacked structure in which the electrode terminals of the battery cells are connected in series with each other and the electrode terminal connections are bent such that the battery cells are stacked; and a pair of cell covers (211 and 212) for restraining the repetitive expansion and contraction change of the battery cells during the charge and discharge of the battery cells while protecting the battery cells, wherein the two cell covers (211 and 212) of said pair have an inside structure corresponding to the outer shape of the battery cell stack and are mounted on an outer surface of the battery cell stack having the two battery cells (100a and 100b) overlapping with each other, the two cell covers of said pair surrounding said outer surface excluding the connected electrode terminals (120, 121) of the battery cells and being coupled with each other; and wherein each cell cover (211, 212) has a longitudinal direction between upper and lower ends thereof and a width lateral direction between opposite sides thereof, each cell cover being provided at a main outer surface thereof with a plurality of linear protrusions which are spaced apart from each other in the width lateral direction of the same cell cover, the linear protrusions being located on the same said main outer surface, and wherein the cell covers (211 and 212) have the same shape and have coupling parts (221 and 222) constructed in a bent structure formed symmetrically with respect to a vertical section between the cell covers, such that the cell covers are engaged with each other by elastic coupling of the cell covers, which are pressed while in contact with each other such that the cell covers face each other.