PURPOSE: To make a rear wheel steering angle actuator hard to be influenced by heat by mounting the rear wheel steering angle actuator among a rear wheel steering mechanism on a vehicle in a position separate as far as possible from a muffler of an engine in a rear wheel steerable vehicle.

CONSTITUTION: A rear wheel steering angle actuator 50 is mounted on a vehicle by being installed on a front cross member 32 among sub-frames 30 of left and right rear wheels. Therefore, the rear wheel steering angle actuator 50 is arranged in a position separate from a muffler on the front side of a differential gear 10, and is hardly influenced by heat.