PURPOSE: To protect a coupling device from impact at the time of a small-scale collision or connection of vehicles by providing an energy absorption system in a coupling of either of two vehicle or in the coupling of the two vehicles.

CONSTITUTION: The body of one vehicle A includes a ring-like center part 1 forming a truncated conical supporting surface 2 on a troidal coupling element 13. The upper part of the ring-like center part forms a first cylindrical surface 1A facing the cylindrical surface of a base plate 9B fixed to the body of a vehicle B. A cylindrical vertical edge 10 is formed on the base plate 9B of the vehicle B, and a circular part 12 of triangular cross section, which supports the troidal coupling element 13, is fixed with bolts 11. Then, an energy absorption system 3 is disposed between the upper part of the ring-like center part 1 on the vehicle A side, and the upper part of a supporting member 9 on the vehicle B side on opposite side. The energy absorption system is formed into a honeycomb structure, which is made of ordinary steel.