To provide a system for using a change-key type lock device, which dispenses with total modification of a cylinder lock device main body per se even if a building managing person of collective housing such as a condominium building is frequently changed, can use the lock device main body in the same mode as a perfectly new mode only by changing a key, involves keys packaged in predetermined application order, and eliminates a fear of erroneous application order of the key.

The system for using the change-key type lock device is comprised of the cylinder key formed of an outer cylinder, an inner cylinder, a key insertion slot, first and second sliding holes, first and second pins, a releasable pin, and a releasable pin housing hole, and the key which is exchangeable for another one. The system involves the plurality of exchange keys which are packaged in the predetermined application order, and if one of the exchange keys is skipped, the skipped exchange key is rendered unusable. Thus the exchange keys are packaged such that their application order can be determined beforehand.