. "As illustrated in FIG. 1, the disk drive 10 includes, at a tray unit 11 which can be put into and extracted from a main body of a drive 12, a disk rotation shaft 13 of an optical disk such as a CD-ROM, an optical disk access unit 14 for conducting access (write or read) to the optical disk, a smart media access unit 15 for conducting access (write or read) to a smart media 1 mounted on the media c" . . .