Abstract: A cryogenic coupler includes a socket and a plug that can be detachably inserted into the socket. The socket and the plug have passages for passing a cryogenic medium therethrough, and are provided with valves for blocking the respective passages when the plug is disconnected from the socket. A seal assembly is arranged between opposite end surfaces of the socket and the plug. The seal assembly has a resilience characteristic that is substantially uninfluenced by the cryogenic temperature, and thus prevents leakage of the cryogenic medium to outside, when passages in the socket and the plug are connected to each other. The coupler allows a facilitated connection and disconnection of the passages, even under a low temperature condition.