PURPOSE: To enable to indicate accurate temperature with simple structure, by indicating temperature, at the same time, controlling temperature by the electric current flowing through a sensor which controls the temperature, in a controlling device for an apparatus to take warmth such as an electric blanket.

CONSTITUTION: A temperature sensing heater of single line type used for an electric blanket and the like is composed such that a core wire is wound by a heater 2, which is covered by a sensor 3 consisting of a plastic thermistor, around which a temperature sensing and detecting electrode wire 4 is wound. A temperature detecting circut 13 to detect the current flowing to a sensor 3 and to convert it into a direct current voltage, a temperature setting circuit 20 to set a temperature to control a heater 2, and a signal processing circuit 24 to compare both outputs from circuits 13 and 20 with each other and to energize and deenergize an electric power controlling element 27 to control power supply to a heater 2, are respectively provided to the control circuit of the above-mentioned temperature sensing heater. And a temperature indicator 12 such as an AC meter is provided to the path for electric current to a sensor.