PROBLEM TO BE SOLVED: To contrive high precise speed controller in the case where a speed difference is large by making a carrier pulse frequency for controlling a motor controller in duty high at the time of low speed slide as compared with the time of high speed slide. SOLUTION: The rotation pulse signal of a motor 7 is detected with a motor controller 8, the speed of a slide door 1 is found from a cycle, a duty is increased and decreased for a target speed, and a drive pulse is output to the motor 7. The cycle required for one rotation of the motor 7 is calculated every pulse input to monitor a change, and the timing of duty updating synchronized with the carrier pulse for controlling the duty. The carrier pulse frequency is switched in response to the slide target speed of the slide door 1, and the frequency is higher in the case where the target speed is relatively low. Thereby even at the time when the door is low speed and slid, speed control is performed in precision near the high speed, and a sense of incompatibility of operation due to response delay, the delay of pinching detection or the like can be prevented.