A battery cartridge includes a pair of outer frame members for receiving unit cells and an inner frame member disposed between the outer frame members. The unit cells are mounted between the outer and inner frame members. The inner frame member has a plurality of through-holes, which communicate with the outside while the unit cells are mounted between the outer and inner frame members. An opened type battery module includes such a battery cartridge. The battery cartridge and the battery module have a high structural integration and mechanical strength. Consequently, the present invention has the effect of minimizing the size of a battery system, stably mounting unit cells having low mechanical strength, and effectively removing heat from the unit cells.