A buffer container (71) is connected to an outflow port (33) of an expansion mechanism (60). The buffer container (71) is shaped like a cylinder extending in the direction of refrigerant flow and has a greater transverse cross sectional area than that of the outflow port (33). The buffer container (71) contains therein a flow stabilizing plate (75) having a mesh part (75a) shaped like a circular plate. The variation in pressure is reduced by pressure supply and pressure absorption by the buffer container (71) and, in addition, refrigerant droplets are made fine in size during passage through the flow stabilizing plate (75).