PURPOSE: To enable heating to an extent where no abnormal overheating is caused without completely stopping the heating even if a temperature sensor becomes abnormal.

CONSTITUTION: The temperature controller which detects the temperature of a part to be detected with the temperature sensor 1 and automatically control the temperature of a heating part heating the part to be detected on the basis of the temperature detected by the temperature sensor 1 is provided with a normal control path 2 which controls power supply to the heating part when the temperature sensor 1 is normal. Further, the controller is provided with an abnormality control path 3 which decreases the rate of power supply to the heating part when the temperature sensor 1 is abnormal, an abnormality detection part 4 which detects the abnormality of the temperature sensor 1, and a switching part 5 which is automatically switched to the side of the normal control path when the temperature sensor 1 is normal and to the side of the abnormal control path 2 once the abnormality detection part 4 detects the abnormality of the temperature sensor 1.