PURPOSE: To control temp. with high accuracy, in the control of the temp. of a centrifugal separator separating a sample using centrifugal force generated by rotating the rotor loaded with the sample attached to a rotary shaft at a high speed, by automatically judging the magnitude of load and continuously operating a freezer when high load operation is judged and controlling the amount of the cooling medium to an evaporator by a switch and a bypass pipe.

CONSTITUTION: Pipings provided with pressure piping and high pressure piping are provided to a freezer constituted of a compressor 7, a condenser 8, a throttle mechanism 13 and an evaporator 10. A load state is judged on the basis of the data obtained by a temp. sensor by a CPU and the way of the cooperation of the condenser 8 and the switching device 12 is changed over to control temp. with high accuracy corresponding to the magnitude of load.