PURPOSE: To effectively utilize a battery by reducing the speed of the oil which flows in a no-load circulation oil passage and reducing the no-load loss.

CONSTITUTION: An electric motor 50 is driven by receiving electric power from a battery loaded on a car through a speed controller 40. A hydraulic pump 60 generates pressurized oil by receiving the rotary power of the motor and feeds oil into a no-load circulation oil passage 72. An oil-pressure controlling part 70 feeds in branched form the pressurized oil formed in the hydraulic pump 60 into an oil feed and discharge passage 74 in accordance with an external operation signal, and operates a power cylinder 80. When a power steering apparatus is judged to be in no-load state by a negative pressure sensor 90, the output of the motor 50 is reduced by the speed controller 40. Therefore, in no-load state, the speed of the oil which circulates in the no-load circulation oil passage 72 is reduced by reducing the revolution speed in comparison with the speed in the case when speed is not controlled at all, and no-load loss is reduced.