PURPOSE: To provide the temperature controller which can perform stable temperature control by putting a cooling-side actuator in operation without any delay when the temperature of a body to be controlled needs to be lowered and also preventing interference between heating and cooling.

CONSTITUTION: Control means 15a and 15b which find manipulated variables of actuators from the output of a comparing circuit 12 comparing the actual temperature of the body to be controlled with set temperature and output the calculated variables are provided for heating-side and cooling-side actuators 4 and 5 respectively. Then this device is equipped with a switching control means 23 which connects the outputs of the control means to the actuators through contacts H and C respectively and makes those contacts selectively according to the output of the comparing means 12 and a correcting means 24 which calculates and sets a correction value for the manipulated variable of the heating-side control means 15a according to the actual temperature of the controlled body and the manipulated variable and set temperature of the heating-side control means 15a when the operation is switched from the cooling side to the heating side by the switching control means 23.