To make an automatic stopping time of a disk rotating motor variable, for example, at the time of a using state of the device equipped with an HDD (hood disk drive) and an at the time of a nonusing state of the device respectively in monitoring the using/nonusing state of the device for the purpose of improving both power saving and operability.

When using a system by the user is recognized, high probability of access to the HDD is judged by a CPU 10 to reset an HDD timer register 22b, so as not to automatically stop the disk rotating motor 17M. When an input operation of the user is not performed, and the HDD timer register 22b is counted down to '0' by a timer 20, a motor-off instructing data is set in a motor-off register (DMOFF) 17b in the HDD by interruption processing of this timer, and the disk rotating motor 17M is controlled to be automatically stopped in accordance with this instructing data.