A recording medium drive device (6) able to be loaded with a recording medium cartridge (100) including a case (101) on which is slidably supported a shutter (110) for opening or closing an opening (101h) for recording information onto a disk-shaped recording medium (200) or reading information recorded on said recording medium, in which is formed a function expansion groove (104), and in which said recording medium is accommodated,
- recording medium drive device provided with:
- a holder (8) for holding said recording medium cartridge when said recording medium cartridge (100) is inserted and
- a shutter opening piece (32d) provided in said holder (8), which shutter opening piece slides said shutter (110) supported upon the case (101) of said recording medium cartridge to open said opening (101h) when said recording medium cartridge (100) is normally inserted into said holder (8) and strikes the opening edge of said function expansion groove (104) of said case (101) of said recording medium cartridge when said recording medium cartridge (100) is inserted into said holder (8) in an erroneous direction to prevents erroneous insertion of said recording medium cartridge into said holder (8).