PURPOSE: To simplify constitution of the circuit of an invertor and carry out an emergency stop test without enlarging the capacity and the number of components at operating an elevator with heavy load in a short time by providing a transformer to lower output voltage of an alternating current power source between the invertor and a winding motor.

CONSTITUTION: At testing emergency stop, a speed command is given from a speed command generating device 26. A control circuit 27 generates a PWM signal from output of a voltage detecting circuit 28, drives the transistor of a converter 22 through a drive circuit 30, and controls the voltage of a smoothing condenser 23 to be a constant value. Further, the control circuit 27 outputs a PWM signal of constant frequency to a drive circuit 29, and the output signal of the drive circuit 29 drives the transistor of an invertor 24. The output current of the invertor 24 is amplified by means of a stepdown transformer 25 and let flow to a motor 7, and as a result of this, the motor 7 can generate large torque. Consequently, it is unnecessary to enlarge the invertor, so as to obtain economical effect.