The present invention includes: a control initiation-stop determiner which receives an initiation-stop request signal for controlling initiation and stop of a motor and information on the number of revolutions of the motor and which outputs a state signal for switching a state of a drive voltage among three states of control stop, control initiation, and control start; and a drive voltage controller which gradually increases a phase current supplied to the motor by using a PWM signal while the state signal causes the state of the drive voltage to transition from control stop to the control initiation and then to the control start.