A vehicle steering system includes a front hydraulic actuator for steering front wheels, a rear hydraulic actuator for steering rear wheels, a front control valve of an open center type for controlling the fluid pressure of the front actuator, a rear control valve of the open center type for controlling the fluid pressure of the rear actuator, a common fluid pressure source, and a flow dividing valve for dividing a fluid flow from the common pressure source into two flows directed to the front and rear control valves so that the front and rear control valves of the open center type can control the fluid pressures independently and accurately.