A library controller including a storage executes first registration processing of, in a case where registration completion information indicating registration completion in a cartridge management system is not stored in a cartridge memory provided in a cartridge, registering identification information for identifying the cartridge and the registration completion information in the cartridge memory, overwriting prohibition processing of prohibiting overwriting to the identification information and the registration completion information registered in the cartridge memory, second registration processing of registering the identification information in the storage, and execution processing of executing reading and writing of user data from and to the cartridge in a case where the identification information stored in the storage coincides with the identification information stored in the cartridge memory.

A library controller including a storage executes first registration processing of, in a case where registration completion information indicating registration completion in a cartridge management system is not stored in a cartridge memory provided in a cartridge, registering identification information for identifying the cartridge and the registration completion information in the cartridge memory, overwriting prohibition processing of prohibiting overwriting to the identification information and the registration completion information registered in the cartridge memory, second registration processing of registering the identification information in the storage, and execution processing of executing reading and writing of user data from and to the cartridge in a case where the identification information stored in the storage coincides with the identification information stored in the cartridge memory.