HARD DISK DEVICE

PURPOSE:To constitute the device so that the security control function is secured, the setting change of the device number can be executed, and the connection change can be facilitated by using the device number of the hard disk device which can be set by a user, and the device number of an information processor. CONSTITUTION:The device is provided with a device number setting means S1 for setting a device number of an information processor, a device number reading means S3 for reading in the device number of the information processor, and a device number comparing means S5 for comparing the device number set by the device number setting means S1, and the device number of the information processor read in by the device number reading means S3. In such a state, by the device number comparing means S5, the comparison between the device numbers is executed, and in the case the device numbers coincide with each other, an operation processing to the information processor can be executed. Accordingly, by using the device number of the hard disk device which can be set by a user and the device number of the information processor, a security control function of a file in the hard disk device is secured.