PURPOSE: To raise the reliability of control by a method in which two relays for power supply to normal and reverse directions of motor are directly controlled by separating unrelated side from power source for auto mode.

CONSTITUTION: The first and second relays 9 and 10 for forming normal and reverse electrifying paths of a motor 8 are provided. The first and second semiconductor switching elements 48 and 49 forming electrifying paths to the relay coils 9b and 10b of the relays 9 and 10 are also provided. During operation for manual mode, the motor 8 is turned normal or reversely through the elements 48 and 49. Also, during operation for auto mode, unrelated one of the elements 48 and 49 is separated from power source by operating an auto made switch 4, whereby obviating the occurrence of maloperation.