PURPOSE: To provide possibility for a vehicle tracted turning easily even on a small rod by arranging wheels of the vehicle so that they can be steered by the steering device of the tractor.

CONSTITUTION: Driver's seat of a tractor 3 is equipped with a steering device 4 for the vehicle to be tracted 1, which is furnished with a rudder device 5 to be operated by said steering device 4. This rudder device 5 is composed of a reversible motor 501 furnished under the rear body of the vehicle to be tracted 1, an intermediate shaft 502, an electromagnetic brake 506 and a reducing rotational shaft 508, where rotation of the reversible motor 501 shall expand and contract the shaft 510 and rod 514. Thus the knuckle arm 512 can be swung fore and aft.