The phase of a drive current of a motor is optimized. The phase arithmetic unit PHCAL calculates a drive voltage phase θdrv to converge the phase difference between the reference voltage phase θbemf and the reference current phase θi to zero based on a prescribed arithmetic expression. The phase correction unit PHCP determines the phase θdrvR after the correction by adding a correction value to the phase θdrv, and the magnitude of the correction value is updated by a feedback control so as to converge to a prescribed value the phase difference between the reference voltage phase θbemf and the reference current phase θi which are inputted. A PWM controller shifts an energization control timing synchronized with the reference voltage phase θbemf based on the corrected phase θdrvR, and generates the PWM signal for controlling the drive voltage to a sine wave shape.