To keep a vehicle body almost at a central position in the lateral direction for preventing occurrence of impulsive force by a contact of the vehicle body with a stopper by generating the force kept almost at a central position in the lateral direction against the displacement force of the vehicle body in the lateral direction to a truck while it is running through the curved sections of tracks.

While a railway vehicle is running on tracks 26, centrifugal force and centripetal force are almost cancelled by each other at the upper surface part of a diaphragm type air spring 24. At the lower surface part 35 of the diaphragm type air spring 24, the air spring 24 receives only centripetal force by cant angle 0, therefore, centrifugal force is not cancelled. The air spring 24 has flexibility in the lateral direction, therefore the diaphragm type air spring 24 is deflected to the outside in the turning direction because of centrifugal force of no cancellation, so that the vehicle body 14 deflects to the outside in the turning direction. By the centripetal force canceling the centrifugal force of no cancellation is applied to the vehicle body 14, the vehicle body 14 is maintained at the central position in the lateral direction even while turning.