PURPOSE: To reduce reactice force to the steering operation by allowing a controller to control an actuator on the basis of the steering force pattarn, which has been set in accordance with the running speed, total weight, etc., and by selecting one of the steering force patterns which suits best to the driver.

CONSTITUTION: A reactive force adjusting valve 15 is composed of a valve casing 18 equipped with a rotor bore 19, a pair of throat ports 20, 21 in communication with this rotor bore 19, and a valve rotor 22 arranged rotatably at this rotor bore so as to adjust the rate of flow of the pressure oil flowing between said pair of throat ports. A pair of reaction passages 16, 17 connect a pair of reaction chambers 53, 54 of a control valve 13 with abovementioned port pair 20, 21, respectively, of the reactive force adjusting valve 15. A controller 73 controls an actuator 23 on the basis of steering force pattern set in relation to the running speed, total weight, etc. and select one of the steering force patterns.