PURPOSE: To provide a railroad coupling of tight self-couple type in good simulation of a real railroad car by structuring so that the frame and hook of one of a pair of couplers to be coupled are opened and closed by their own resilience, and installing a cam to open the frame and hook between the two couplers.

CONSTITUTION: When two model cars to be coupled are approached to each other, the back 24a of each knuckle 24 collides with one surface 31a of an inward facing projection 31, and also knuckles 24 run against each other. The trunk parts of a coupler frame 2 and coupler hook 3 deflect in the direction of opening the coupler frame 2 and coupler hook 3, and the inward facing projection 31 of the coupler hook 3 drops into a recess 23 to cause the couplers 1 to be coupled together. If the model cars are separated from each other, on the other hand, the inner surface 23a of the recess 23 is contacted with the other surface 31b of the projection 31, and the drums deflect in the direction of opening the coupler frame 2 and coupler hook 3 to cause the projection 31 to be set off from the recess 23.