Disclosed herein is a battery cartridge for middle- or large-sized battery packs, which has one or more unit cells mounted therein. The battery cartridge is generally constructed in a plate-shaped structure for easy stacking, and connecting members for electrical connection between cartridges are constructed in a coupling structure in which the connecting members are coupled with each other during the stacking of the cartridges. When a plurality of cartridges are stacked one on another so as to construct a middle- or large-sized battery pack, the mechanical coupling between the cartridges is accomplished, and, at the same time, the electrical connection between the cartridges is also accomplished, whereby the assembly of the cartridges is easily accomplished, and the risk of short circuits is prevented during the assembly or the use of the cartridges. Furthermore, a middle- or large-sized battery pack manufactured using the battery cartridge according to the present invention has a stable compact structure. Consequently, the middle- or large-sized battery pack is preferably used as a power source for electric vehicles or hybrid electric vehicles.