Phase correction unit (25) for outputting a commutation signal for switching a winding that allows a current to flow to brushless DC motor (4) and drive unit (16) for outputting a drive signal indicating supplying timing of electric power supplied to brushless DC motor (4) by inverter (3) based on the commutation signal output from phase correction unit (25) are provided so as to maintain a predetermined relation between a phase of a current flowing to a predetermined winding of brushless DC motor (4) and a phase of a voltage. Since brushless DC motor (4) is driven by a signal for holding the predetermined relation between the phase of the current and the phase of the voltage, the stability of drive under high-speed and high-load conditions is enhanced and a drive range is extended.