A prismatic battery cell comprising a cap plate, a prismatic cell case and an electrode assembly configured to have a structure in which a separator is disposed between a cathode and an anode, wherein the cap plate is mounted at an open top of the prismatic cell case in a state in which the electrode assembly is mounted in the prismatic cell case, the cap plate is provided with an anode terminal or a cathode terminal as a protruding terminal, and the prismatic cell case is configured to have a structure in which two or more case members (230a, 230b, 330a, 330b) divided in a major axis direction, in a minor axis direction, or in the major axis direction and the minor axis direction based on a horizontal sectional shape of the cap plate with respect to the protruding terminal are coupled to each other, characterized in that the case members (230a, 230b, 330a, 330b) are manufactured by bending a metal sheet such that the metal sheet has a shape corresponding to the cell case, the cell case is manufactured by welding an interface between the case members (230a, 230b, 330a, 330b) in a state in which the case members (230a, 230b, 330a, 330b) are in tight contact with each other so as to have a shape of the cell case such that contact ends (340a, 340b) of the case members (330a, 330b) overlap each other and the overlapped contact ends (340a, 340b) of the case members (330a, 330b) are rolled such that the sum of thicknesses of the overlapped contact ends (340a, 340b) is equal to the thickness of any one of the case members (230a, 230b, 330a, 330b) and then the interface between the case members (230a, 230b, 330a, 330b) is welded, and the cell case and the cap plate are made of aluminum or an aluminum alloy. the cap plate is mounted at an open top of the prismatic cell case in a state in which the electrode assembly is mounted in the prismatic cell case, the cap plate is provided with an anode terminal or a cathode terminal as a protruding terminal, and the prismatic cell case is configured to have a structure in which two or more case members (230a, 230b, 330a, 330b) divided in a major axis direction, in a minor axis direction, or in the major axis direction and the minor axis direction based on a horizontal sectional shape of the cap plate with respect to the protruding terminal are coupled to each other, characterized in that the case members (230a, 230b, 330a, 330b) are manufactured by bending a metal sheet such that the metal sheet has a shape corresponding to the cell case, the cell case is manufactured by welding an interface between the case members (230a, 230b, 330a, 330b) in a state in which the case members (230a, 230b, 330a, 330b) are in tight contact with each other so as to have a shape of the cell case such that contact ends (340a, 340b) of the case members (330a, 330b) overlap each other and the overlapped contact ends (340a, 340b) of the case members (330a, 330b) are rolled such that the sum of thicknesses of the overlapped contact ends (340a, 340b) is equal to the thickness of any one of the case members (230a, 230b, 330a, 330b) and then the interface between the case members (230a, 230b, 330a, 330b) is welded, and the cell case and the cap plate are made of aluminum or an aluminum alloy.