A battery module case set comprising: a first battery module case comprising a frame element and a plurality of first battery cells being stacked in the frame element, the frame element including rectangular frames connected together by first and second face plates (15a, 15b) at both ends thereof, wherein the first face plate has a first cutout portion being formed therein such that an upper end surface of one of the first battery cells which is adjacent to the first face plate is exposed and wherein the second face plate has a second cutout portion such that a lower end surface of one of the first battery cells which is adjacent to the second face plate is exposed; and a second battery module case comprising a frame element and a plurality of second battery cells being stacked in the frame element, the frame element including rectangular frames connected together by first and second face plates (15a, 15b) at both ends thereof, wherein the first face plate has a first cutout portion being formed therein such that an upper end surface of one of the second battery cells which is adjacent to the first face plate is exposed and wherein the second face plate has a second cutout portion such that a lower end surface of one of the second battery cells which is adjacent to the second face plate is exposed; wherein the first battery module case and the second battery module case are arranged adjacent to each other so that the first face plate of the first battery module case confronts the second face plate of the second battery module case, wherein the first cutout portion of the first battery module case and the second cutout portion of the second battery module case define a passage in which cooling fluid can flow between the first face plate and the second face plate. a first battery module case comprising a frame element and a plurality of first battery cells being stacked in the frame element, the frame element including rectangular frames connected together by first and second face plates (15a, 15b) at both ends thereof, wherein the first face plate has a first cutout portion being formed therein such that an upper end surface of one of the first battery cells which is adjacent to the first face plate is exposed and wherein the second face plate has a second cutout portion such that a lower end surface of one of the first battery cells which is adjacent to the second face plate is exposed; and a second battery module case comprising a frame element and a plurality of second battery cells being stacked in the frame element, the frame element including rectangular frames connected together by first and second face plates (15a, 15b) at both ends thereof, wherein the first face plate has a first cutout portion being formed therein such that an upper end surface of one of the second battery cells which is adjacent to the first face plate is exposed and wherein the second face plate has a second cutout portion such that a lower end surface of one of the second battery cells which is adjacent to the second face plate is exposed; wherein the first battery module case and the second battery module case are arranged adjacent to each other so that the first face plate of the first battery module case confronts the second face plate of the second battery module case, wherein the first cutout portion of the first battery module case and the second cutout portion of the second battery module case define a passage in which cooling fluid can flow between the first face plate and the second face plate.