To enhance the stability of straight running and also the on-curve passing performance by installing a damper able to control the force acting between car bodies in a coupling structure for the bodies with each other of cars to run on a track.

The arrangement according to the present invention comprises a displacement sensor to sense the relative displacement of car bodies relative to each other, the damper installed between the car bodies and able to control the force acting on the bodies, and a control device to be fed with the relative displacement sensed by the displacement sensor, judging whether the cars are running on a straight track or on a curved track on the basis of the relative displacement, the relative speed calculated on the basis of the relative displacement or the frequency of the relative displacement, and operating the damper 6 so as to reduce the vibration when the cars run on the straight track, and when on the curved track, operating so as to assist the body yawing motion.