It is required that setting information and mechanical correction information of a preceding device can be automatically carried over only by replacing a unit, to implement reduction in the maintenance cost and prevention of human operational mistakes. Library device control firmware 11 updates, if drive identification information kept in a library control unit 10 differs from drive identification information kept in two other units on the basis of logic of decision by majority, a drive serial number 4A and device setting information 2A kept in the library control unit 10 based on a drive serial number 4B and device setting information 2B kept in an accessor control unit 20.