A temperature sensitive rod is communicated with a diaphragm that is displaceable in response to a pressure difference between an internal pressure of a sealed space, in which a temperature sensitive medium is sealed, and a pressure of a low pressure refrigerant outputted from an evaporator. A blind hole, which opens to the sealed space, is formed in an inside of the temperature sensitive rod. The temperature sensitive medium is a mixture gas of the refrigerant and an inert gas. A mixing ratio of the inert gas in the temperature sensitive medium corresponds to a ratio of an equivalent diameter of the blind hole relative to a depth of the blind hole in such a manner that a time constant of heat conduction from the temperature sensitive rod to the temperature sensitive medium is kept within a desired time constant range.