When a guard timer of a compressor (141) expires, an R2 signal from a control section (140) of an outdoor unit is turned on (Action I). If a control section (120) of a freezer unit recognizes from an inside temperature detected by a temperature sensor (124) that the R2 signal is turned on and a request for a shift to a freezer thermo-on state is raised (Action II), a freezer electromagnetic valve (121) is opened (Action III). In general, when the electromagnetic valve (121) is opened, it is supposed that an increase in refrigerant suction pressure is detected by a pressure sensor (146) and then the compressor (141) is actuated. However, if an outside air temperature is low, the refrigerant suction pressure remains lower than a predetermined value. Therefore, the control section (120) actuates a booster compressor (131) (Action IV) to raise the refrigerant suction pressure of the compressor (141).