Disclosed is a cartridge drop detection device for use in a magnetic tape library apparatus (11) comprising a media rack (14) for accommodating at least one cartridge containing a magnetic tape medium (16), a tape drive (15) for holding the magnetic tape medium when reading from or writing to the magnetic tape medium, and a robot for retrieving the cartridge from the media rack and for transporting the cartridge to the tape drive, wherein the cartridge drop detection device comprises: a microphone (18), installed on a floor (20), for detecting that the cartridge has dropped on the floor of the tape library apparatus; a vibration detection sensor (17) for detecting vibration applied to the tape library apparatus; and a detection circuit for determining that the cartridge has dropped on the floor when a voltage detected by the microphone and a voltage detected by the vibration detection sensor have exceeded respective threshold values, whereby providing a device which can reliably detect whether any cartridge in the magnetic tape library apparatus has dropped or not.