PURPOSE: To make it possible to easily and accurately determe the mixing ratio of the refrigerants during operation of a refrigerating device.

CONSTITUTION: The subject relates to a refrigerating device having a refrigerant circuit in which a compressor 1, condenser 2, expansion mechanism 3, and evaporator 4 are connected and through which a nonazeotropic mixture of refrigerants is circulated. In this refrigerating system there are provided a pressure detector 5 which detects the discharge pressure of the compressure 1 and a plurality of temperature detectors 7, 8 which detect the temperatures of the refrigerant inside the condenser 2 at a plurality of spots positioned therein with specified distances apart from the condenser exit 2a. From the ratio of the differential temperature of the refrigerant detected by these temperature detectors 7, 8 to the difference between the distances from the condenser exit 2a to the respective temperature detectors 7, 8 the gradient of a change in temperature of the refrigerant inside the condenser 2 is obtained. Furthermore, there are provided a first calculating means and a second calculating means: the first calculating mans is for obtaining the condensing saturation temperature of the refrigerant at the condenser exit 2a on the basis of the above-mentioned gradient and the second calculating means is for obtaining the mixing ratio of the refrigerants on the basis of the condensing saturation temperature determined by the first calculating means and the discharge pressure detected by the pressure detector 5.