PURPOSE: To minimize the power consumption for power steering and effect energy saving by operating an oil pump only when a large steering force is required and without operating said pump when a car is stopped and there is no need of steering.

CONSTITUTION: When a car starts to run, a car-speed sensor 100 genrates speed signals and a timer 200 generates motor driving signals regardless of steering operations, turning a switch 7 on. An F-V convertor 220 generates a DC voltage corresponding to the speed signals, but during the time when the speed signals are below the determined value, a comparator 240 does not generate motor cut- off signals, a switch 6 is turned on and a motor 3 continues to operate. When the determined speed is over, the voltage supplied from the F-V convertor 220 to the comparator 240 exceeds its set value causing the comparator circuit 240 to generate motor cut-off signals. Thereby the switch 6 is turned off and the motor 3 stops operating without the electric power being provided.