PURPOSE: To obtain refrigerating plant of which the refrigerating performance is prevented from deteriorating due to a contaminant being present in a refrigerant.

CONSTITUTION: The main part of a capillary tube 17 of an expansion mechanism of a refrigeration cycle is constructed of a thin straight pipe 24. Therefore the flow of a refrigerant passing through the capillary tube 17 becomes uniform in the thin straight pipe 24 of the main part. Since a flow velocity is different in a passage section, a contaminant in the refrigerant is unevenly distributed in the flow and sticks on the internal wall surface of the capillary tube 17. This state is eliminated in the thin straight pipe 24 of the main part. Thereby deposition of the contaminant present in the refrigerant on the internal wall surface of the capillary tube 17 is suppressed and a refrigerating performance is prevented from deteriorating.