To directly connect a hard disk drive unit and an optical disk drive unit interposing an MPEG substrate therebetween.

The hard disk drive unit 2 and the optical disk drive unit 3 are installed side by side inside a case 1. The MPEG substrate 35 for controlling the optical disk drive unit 3 is fixed onto the hard disk drive unit 2. A wiring cord 37 for connecting the MPEG substrate 35 and the hard disk drive unit 2 and a flexible cable for connecting the MPEG substrate 35 and the optical disk drive unit 3 are electrically connected by a conductive path 39 formed on the MPEG substrate 35. The conductive path 39 is electrically connected to a microcomputer 16. The data communication between the optical disk drive unit 3 and the hard disk drive unit 2 can be performed by the microcomputer 16 by relaying the MPEG substrate 35.