To provide a medium library device or the like for enabling a user to know contents of a cartridge even without mounting the cartridge in a disk drive with an inexpensive configuration.

A cartridge 10 has a barcode 12 including an identification number and a cartridge memory 13 storing management information representing contents of a storage medium, a disk drive 30 includes a cartridge memory reading part 31, conveyance means 40 includes a barcode reading part 41 for reading a barcode on a conveying part 42, and managing means 50 includes a storing part 52 for associating the identification number read from the barcode with the management information read from the cartridge memory for storage, a medium information managing part 61 for retrieving management information corresponding to a new identification number read from the barcode, and an inputting and outputting part 53 for displaying the retrieved management information. The barcode reading part 41 is provided on a cartridge conveyance entrance side of the conveying part.