To provide a torque ripple reduction method which can detect a position of a rotor of a switched reluctance motor(SRM) by utilizing one position sensor only and reduce a torque ripple of the SRM.

A step in which a pulse of a position detection signal corresponding to a detection result of a position of a rotor of a motor SRM is set, a step in which signals controlling currents of respective phases are outputted synchronously with the rising and falling edges of the position detection signal are outputted, and a step in which a pulse width modulation signal with a variable duty ratio is outputted since a time when the falling edge of the position detection signal is detected, are successively carried out to reduce a torque ripple of the motor.