To provide a check valve having simple construction for distributing low temperature fluid in only one direction, and to provide a low temperature fluid pump.

A first check valve (the check valve) 10 comprises a valve element 12, a valve seat 13 arranged in the direction of the gravity of the valve element 12 to be placed thereon, and a valve element supporting part 16 for supporting the valve element 12 on the valve seat 13. The valve element 12 has a protruded portion 17 extending to the opposite direction to the direction of the gravity of the valve element 12. The valve element supporting part 16 has a guide portion 20 fitted to the protruded portion 17 for restricting the movement of the valve element 12 only in the longitudinal direction of the protruded portion 17, and an auxiliary guide portion 21 provided coaxially with the guide portion 20 and fitted to the protruded portion 17 for restricting the run-out of the protruded portion 17 from the valve element supporting part 16.