PURPOSE: To improve the displacing property of a vehicle through a front and rear wheel steering device capable of altering the ratio of steered angle of rear wheels to front wheels depending on the speed of the vehicle, by enabling the manual alteration of the steered angle ratio to a desired value only when the vehicle speed is low.

CONSTITUTION: When the speed of a vehicle is over a prescribed level, the output of information for manual modification of steered angle ratio is stopped. In other words, when the vehicle speed is over the prescribed level during the modification of the steered angle ratio under automatic operation, this automatic operation is maintained even if the steered angle ratio is attempted to be manually modified. Vehicle speed data for such control are chosen in consideration of a very low speed necessary to perform the parking of the vehicle between others in tandem, the sideward displacement of the vehicle, etc.