A highly reliable refrigeration cycle having a residual refrigerant, which is designed that the refrigerating machine oil does not stagnate in the refrigeration cycle after flowing out from the compressor even if the refrigerating machine oil is weakly soluble in a refrigerant. Thus, the compressor may be prevented from the exhaustion of oil. In addition to that, even if the accumulator is removed from the cycle, a large amount of wet vapor suction into the compressor may also be avoided. A control section is provided for controlling saturated oil solubility in a liquid refrigerant in the refrigeration cycle. The control section includes a receiver and first and second flow regulators which are placed before and after, respectively, the receiver. A residual liquid refrigerant obtaining in the circulation of a refrigerant is reserved in the receiver at a high temperature so that the weakly soluble refrigerating machine oil is prevented from separating.