PURPOSE: To make a forward or reverse operation of a motor based on an external command signal which is input into a contactor for forward operation or a contactor for reverse operation and to eliminate a mechanical electromagnetic contactor and reduce the size of the motor by outputting a temperature detection signal from a temperature detector of a stator winding.

CONSTITUTION: When a control signal is input into a first control terminal 27, a contactor for forward operation 13 is turned on and then the three-phase power is supplied to an induction motor M and the induction motor M rotates in the forward direction. When a control signal is input into a second control terminal 28, a contactor for reverse operation 14 is turned on and then the three-phase power with an R phase and a T phase reversed is supplied to the induction motor M and the induction motor M rotates in the reverse direction. From an output terminal 29, a temperature ditection signal of a temperature detector 15 is output. When a controller receives the temperature detection signal and confirms that the signal is in an on state, it rapidly opens the contactor for forward operation 13 and the contactor for reverse operation 14. In other words, the controller turns the control signal off and cuts off the power to the induction motor M.