PURPOSE: To simplify the whole circuit constitution by providing the third operational amplifier and using it for both charging and discharging of a simultaneous starting prevention condensor.

CONSTITUTION: When power is turned on, the first operational amplifier 3 becomes ready for priority starting by a condition setting condensor C3 and the first compressor 6 is operated in preference to the others. When the ampli fier 3 is operated, the third operational amplifier 5 is operated through a diode to generate simultaneous starting prevention signal following charging to a simultaneous starting prevention condensor C2. By this, the second operational amplifier 4 is stopped to operate and simultaneous starting can be prevented. Also, during normal operation, the compressor, to which a signal is transmitted firstly from either one of a temperature control circuits 1 and 2 is started imme diately and the compressor, to which a signal is transmitted later, is started after such a time as equivalent to the time for charging to the starting preven tion condensor C2. When both compressors 6 and 7 are stopped, the power of the third amplifier 5 is reduced and the charge of the condensor C2 is re leased immediately.