PURPOSE: To prohibit the adjustment of vehicle height in steering to improve safety by utilizing a power steering hydraulic pump for a hydraulic source for adjusting the vehicle height so that oil pressure supply to the power steering gear by the hydraulic pump has a priority in steering operation.

CONSTITUTION: On the way of an oil path 3 connected to the discharge side of a hydraulic pump 1 are provided a flow control valve 13 and an electromagnetic change-over valve 4 to the discharge side of which are connected a power steering gear 5 and a vehicle height adjusting hydraulic damper 7 through oil paths 6, 8. A solenoid in said valve 4 is controlled by a controller 9 on the basis of the outputs of a steering angle sensor 10 and a vehicle height sensor 11. Then, this solenoid is controlled to change over the change-over valve 4 to the hydraulic damper 7 side only when the vehicle height is changed so long as steering is not carried out. Thus, the adjustment of the vehicle height in steering is prohibited to ensure and improve the stability and safety of the vehicle in travelling.