To provide a drive unit that suffers from no insertion/removal problem of an automatic conveying mechanism in the drive unit installed in a library device accommodating a plurality of recording medium cartridges which are inserted and removed by the automatic conveying mechanism, and executes the recording and reproduction of information to the inserted recording medium cartridge.

The drive unit is provided with a front bezel (bezel) 31, which is arranged with its position adjustment possible to an insertion aperture part, in which an aperture which the recording medium cartridge 23 is inserted in and removed from is formed, and faces the aperture, and in which a through hole 33, in which the recording medium cartridge 23 is inserted, is formed. Further, at least one selected from an upper guide 35, a lower guide 37, a first side guide 39, a second side guide 41, which all guide the recording medium cartridge 23 to the through hole 33, and a marker 43 for positioning the automatic conveying mechanism, is formed integrally with the front bezel 31.