PURPOSE: To achieve a reduction in the number of parts and economy in the current consumption of a circuit by deciding on the temperature with one comparator circuit employing a circuit having two different kinds of temperature- output voltage characters.

CONSTITUTION: A circuit is equipped with two temperature sensors, first and second 4 and 5. The first temperature sensor 4 is made up of a semiconductor injunction element and the output voltage VX has a temperature characteristic as illustrated. The temperature sensor 5 combines a thermistor and a resistance and the output VZ thereof has the temperature characteristic as illustrated. The output VX and VZ are respectively connected to the positive phase input and the opposite phase input of a differential amplifier 6 as comparison decision circuit. The output E of the differential amplifier 6 is introduced to an output terminal 7. When discrimination is made between temperatures T1 and T2 as given, the voltage value and the resistance value are determined by a specified equation. This enables the calculation of values R11 and R12 of a resistor realizing a circuit which can obtain a discrimination output E in given temperature ranges T1WT2.