An information processing system which is capable of promptly authenticating a combination of a disk array device accommodating a plurality of disk devices, and an information processing apparatus in which the disk array device is mounted. A first control section of a cartridge device as a disk array device stores ID information for use in authentication by an information processing apparatus, and a second control section of the information processing apparatus acquires the ID information from the first control section. The second control section authenticates the cartridge device by using the acquired ID information. A third control section of the information processing apparatus reads out information from hard disk devices contained in the cartridge device when the authentication by the second control section is successful.