PURPOSE: To relax the driving of an antenna by displaying an alarm when over currents flow to a motor and a braker provided at an AC input line is operated in a DC power source for the motor to drive the antenna at a designated azimuth angle, on the other hand, by lowering the revolution of the motor by lowering the voltage of the DC power source when the antenna is driven near the designated position.

CONSTITUTION: A microcomputer 7 for control monitors a DC power source V1 to drive a motor 12. Since the DC power source V1 is stopped when a braker 1 is operated by any abnormality, the input to the microcomputer 7 is turned to zero as well. At such a time, the microcomputer 7 outputs a signal 24 for display to a display part 8. When it is detected that the antenna is driven near the designated position, the microcomputer 7 outputs a switching signal 21 to a first relay 3 and switches the tap of a transformer 2 to the T1 side. Thus, the DC voltage V1 is lowered, and the revolution of the motor 12 is decreased.