The present invention relates to a recording medium cartridge memory and recording/reproducing apparatus. A recording medium cartridge consists of a recording medium and a cartridge memory in which a unique ID of the apparatus used for recording/reproducing the cartridge memory is recorded in an unrewritable condition. The apparatus for recording/reproducing the recording cartridge memory consists of a sending/receiving unit which reads out an ID recorded in the cartridge memory, an ID inspection unit inspecting whether or not the ID recorded in the cartridge memory and an ID stored in the apparatus accord by comparing both, and a control unit which records data in a recording medium or control operations of a recording/reproducing unit which reproduces data from the recording medium based on an inspection result in the ID inspection unit.