Embodiments of the invention reduce the peak consumption current of a disk drive and that of its application system, and to minimize the limitation of the consumption current so that the performance deterioration of the disk drive and its application system is minimized. In one embodiment, a monitor terminal is provided to enter the pre-regulated output voltage of the voltage constant power supply. The disk drive is controlled so as to suppress the currents consumed by individual sections in the disk drive if the monitored voltage falls to a predetermined reference voltage.