A pack case (100, 300) for battery packs in which a battery cell array comprising two or more battery cells arranged in a lateral direction and a protection circuit module (230, PCM) comprising a protection circuit to control an operation of the battery pack are mounted, the pack case comprising: a lower case, on which the battery cell array and the protection circuit module are mounted; and an upper case disposed above the lower case so that the upper case covers the lower case to fix the battery cell array and the protection circuit module in place, wherein the lower case is partitioned into a battery cell mounting part, on which the battery cells are mounted, and a protection circuit module mounting part, on which the protection circuit module is mounted, a partition wall is formed at an interface between the battery cell mounting part and the protection circuit module mounting part, and openings, through which electrode terminals (222, 224) of the battery cells are exposed toward the protection circuit module, are formed at portions of the partition wall corresponding to electrical connection regions between the electrode terminals of the battery cells and the protection circuit module, and characterized in that the protection circuit module mounting part comprises support parts (126a, 126b, 126c) at the openings of the partition wall to support the electrical connection region between each of the electrode terminals of the battery cells and the protection circuit module, and wherein each of the support parts is formed on the lower case in the shape of an upward protrusion in the shape of a straight protrusion in plan, two parallel protrusions in plan, or a cylindrical boss type protrusion in plan, excluding a cross type protrusion in plan in a state in which the support part is connected to the partition wall. a lower case, on which the battery cell array and the protection circuit module are mounted; and an upper case disposed above the lower case so that the upper case covers the lower case to fix the battery cell array and the protection circuit module in place, wherein the lower case is partitioned into a battery cell mounting part, on which the battery cells are mounted, and a protection circuit module mounting part, on which the protection circuit module is mounted, a partition wall is formed at an interface between the battery cell mounting part and the protection circuit module mounting part, and openings, through which electrode terminals (222, 224) of the battery cells are exposed toward the protection circuit module, are formed at portions of the partition wall corresponding to electrical connection regions between the electrode terminals of the battery cells and the protection circuit module, and characterized in that the protection circuit module mounting part comprises support parts (126a, 126b, 126c) at the openings of the partition wall to support the electrical connection region between each of the electrode terminals of the battery cells and the protection circuit module, and wherein each of the support parts is formed on the lower case in the shape of an upward protrusion in the shape of a straight protrusion in plan, two parallel protrusions in plan, or a cylindrical boss type protrusion in plan, excluding a cross type protrusion in plan in a state in which the support part is connected to the partition wall.