To provide a binary refrigerating plant capable of being started even when using a compressor having a small-torque and small-size motor for reducing power consumption and noises.

The binary refrigerating plant comprises an evaporator 4 in a high temperature side refrigerant circuit H and a condenser 12 in a low temperature side refrigerant circuit L, both of which are provided in parallel. With the heat of evaporation of a refrigerant in the high temperature side refrigerant circuit H evaporating in the evaporator 4, a refrigerant in the low temperature side refrigerant circuit L is cooled and condensed in the condenser 12 and the condensed refrigerant in the low temperature side refrigerant circuit L is evaporated in an evaporator 14, in such a manner that the evaporator 14 develops a temperature further lower than the evaporator 4. To a lower pressure side as the suction side of the compressor 1 in the high temperature side refrigerant circuit H, a refrigerant tank 7 is connected via a connection pipe 6 in which a capillary tube 5 is laid. The sum of the internal volume of the refrigerant tank 7 and the internal volume of the connection pipe 6 ranging from the capillary tube 5 to the refrigerant tank 7 is 30-75% of the total internal volume of the high temperature side refrigerant circuit H.