To rapidly exhaust a large amount of low temperature fluid by forming on a valve member, a second seal surface by which a second lead-through passage is closed when the valve member is seated on a lower wall member, and also forming on the lower wall member, a third seal surface by which a fluid passing hole is closed.

A first seal surface 26 by which a first lead-through passage 7 is closed when a temperature control machine element 9 is seated on the first lead- through passage 7, is formed on a lower wall member 17, and a second lead-through passage 27 having small aperture is formed on the inner side of the first seal surface 27. Then, a second seal surface 28 by which the second lead-through passage 27 is closed when a valve member 16 is seated on the lower wall member 17, is formed on the valve member 16, and also a third seal surface 19 by which a fluid passing hole 20 is closed is formed on the lower wall member 17. At this time, the first seal surface 26 of the temperature control machine element 9 is separated from the first lead-through passage 7 by a thermally-actuated member 24 so as to open the first lead-through passage 7. Hereby, a large amount of low temperature fluid can be rapidly exhausted, and the intermittent operation of an opening/closing valve can be executed, thus condensation may not be mistaken as steam leakage when exhausted.