A recorded data securing mechanism secures data recorded on a recording medium cassette provided with a memory and a data recording enable/disable tab at a predetermined position on the cassette. Breaking the recording enable/disable tab provided on the memory-based recording medium cassette prevents data recorded on the cassette from being written over and ensures that there will be no mismatch between the recording information stored in the memory of the cassette and the data recorded on the recording medium of the cassette. In one embodiment, rewriting is enabled but a memory mismatch flag is set if rewriting results in a mismatch.