PURPOSE: To decrease a cost with structure simplified by providing a motor current detecting part and a clutch on-off discriminating part discriminating a clutch for whether it is on or off from a control mode when a detected motor current increases to not less than a predetermined value.

CONSTITUTION: As a clutch on-off control system, a DC motor 8 connects to its circuit a current detecting resistor 50, and a flow of motor current in this resistor is detected by a current detecting part 51. This motor current and an on-off control mode signal following a direction of motor rotation from a motor control part 46 are input to a clutch on-off decision part 52. Then the clutch on-off decision part 52 judges a clutch for whether it is in a maximum or minimum stroke by the lock current, when the DC motor 8 is locked, and the control mode signal. This judging result is input to a stop control part 44 or 45 stopping the DC motor 8.