A battery module comprising: a plurality of cell stacks, each of the cell stacks comprising: a plurality of unit cells arranged in a first direction; and an insulation member around the plurality of unit cells; and a module housing, in which a plurality of receiving parts are provided, ones of the cell stacks from among the plurality of cell stacks being located in a receiving part from among the plurality of receiving parts, wherein each of the receiving parts comprises a fixing wall, the fixing wall being around the cell stack received therein and being in contact with the cell stack, and wherein the module housing comprises end walls at respective sides of each of the receiving parts in the first direction to engage end surfaces of respective sides of the cell stack received in the respective receiving part in the first direction, wherein the module housing further comprises a separation wall that extends in the first direction and partitions an inner space surrounded by an outer wall of the module housing to form adjacent ones of the plurality of receiving parts along a second direction that is perpendicular to the first direction, and the separation wall corresponds to a part of the fixing wall of the adjacent ones of the plurality of receiving parts, and the separation wall contacts a side surface of the respective cell stacks received in the adjacent ones of the plurality of receiving parts, wherein the end walls comprise a first end wall and a second end wall, and the first end wall faces the outer wall of the module housing and is spaced apart from the outer wall along the first direction, defining a first space between the first end wall and the outer wall, wherein a first receiving part and a second receiving part from among the plurality of receiving parts are arranged along the first direction in the inner space of the module housing, and the second end walls of the first receiving part and the second receiving part are spaced apart from each other and face each other, defining a second space between the second end walls of the first and second receiving parts (220 and wherein the end walls are curved outwardly such that central portions thereof are located further from the end surfaces of the cell stacks than other portions of the end walls, defining a third space between the respective end surface and the respective end wall. a plurality of cell stacks, each of the cell stacks comprising: a plurality of unit cells arranged in a first direction; and an insulation member around the plurality of unit cells; and a plurality of unit cells arranged in a first direction; and an insulation member around the plurality of unit cells; and a module housing, in which a plurality of receiving parts are provided, ones of the cell stacks from among the plurality of cell stacks being located in a receiving part from among the plurality of receiving parts, wherein each of the receiving parts comprises a fixing wall, the fixing wall being around the cell stack received therein and being in contact with the cell stack, and wherein the module housing comprises end walls at respective sides of each of the receiving parts in the first direction to engage end surfaces of respective sides of the cell stack received in the respective receiving part in the first direction, wherein the module housing further comprises a separation wall that extends in the first direction and partitions an inner space surrounded by an outer wall of the module housing to form adjacent ones of the plurality of receiving parts along a second direction that is perpendicular to the first direction, and the separation wall corresponds to a part of the fixing wall of the adjacent ones of the plurality of receiving parts, and the separation wall contacts a side surface of the respective cell stacks received in the adjacent ones of the plurality of receiving parts, wherein the end walls comprise a first end wall and a second end wall, and the first end wall faces the outer wall of the module housing and is spaced apart from the outer wall along the first direction, defining a first space between the first end wall and the outer wall, wherein a first receiving part and a second receiving part from among the plurality of receiving parts are arranged along the first direction in the inner space of the module housing, and the second end walls of the first receiving part and the second receiving part are spaced apart from each other and face each other, defining a second space between the second end walls of the first and second receiving parts (220 and wherein the end walls are curved outwardly such that central portions thereof are located further from the end surfaces of the cell stacks than other portions of the end walls, defining a third space between the respective end surface and the respective end wall.