A variable restrict valve is disposed at the upstream side of a refrigerant flow, a fixed restrictor is disposed at the downstream side of the variable restrict valve, an intermediate space is provided between the variable restrict valve and the fixed restrictor, a passage sectional area of the intermediate space is set to be larger than the fixed restrictor and passage length L of the intermediate space is set to be larger than a predetermined length required when the flow of refrigerant injected from the variable restrict valve expands more than the passage sectional area of the fixed restrictor.