DOOR OPENING/CLOSING DEVICE AND DOOR OPENING/CLOSING METHOD

A door opening/closing device includes a motor and a control unit that controls the rotation rate of the motor by pulse-width modulation (PWM) control. The door opening/closing device opens and closes a door of a vehicle with power of the motor. The control unit performs the PWM control on the motor at a PWM frequency set so as to deviate from a resonance point of an installation body on which the motor is installed. The installation body includes a housing unit that houses the motor, a fixing unit that fixes the door opening/closing device to the vehicle, and the vehicle. Thus, it is possible to provide the door opening/closing device that generates a small sound in an opening and closing operation.