To provide a binary refrigerator capable of sufficiently exercising refrigerating capability.

In the binary refrigerator, since a mixture of nitrous oxide and an HC refrigerant is used as a refrigerant of a low temperature side refrigeration circuit, a mixture of carbon dioxide and the HC refrigerant is used as a refrigerant of a high temperature side refrigeration circuit, a low temperature side gas-liquid separator is provided in an outlet side of a condenser of the low temperature side refrigeration circuit, a low temperature side heat exchanger is provided for cooling an un-condensed refrigerant from a gaseous phase part of the low temperature side gas-liquid separator by a condensed refrigerant from a liquid phase part of the low temperature side gas-liquid separator, a high temperature side gas-liquid separator is provided in an outlet side of a condenser of the high temperature side refrigeration circuit, and a high temperature side heat exchanger is provided for cooling an un-condensed refrigerant from a gaseous phase part of the high temperature side gas-liquid separator by a condensed refrigerant from the high temperature side gas-liquid separator, the un-condensed refrigerants can be condensed by each heat exchanger, and the binary refrigerator capable of sufficiently exercising refrigerating capability can be provided.