PURPOSE: To provide a temperature detecting device which can make accurate temperature measurement with only one thermistor.

CONSTITUTION: When a plurality of temperatures is measured at the time of performing temperature measurement by comparing a voltage dividing signal S7 obtained by dividing a power supply voltage V0 by the resistance ratio between a thermistor 5 and a voltage dividing resistor 6 with a reference temperature voltage 11, the voltage value change of the signal S7 with the unit temperature change becomes smaller on the lower or higher temperature side. In order to perform highly accurate temperature measurement, therefore, a first reference voltage 23 which is lower than the reference temperature voltage 11 and second reference voltage 24 which is higher than the voltage 11 are set and circuit is so structured that, when the voltage of the signal S7 exceeds the second reference voltage 24, the voltage can be dropped to a voltage lower than the voltage 11 and, when the voltage of the signal S7 becomes lower than the first reference voltage 23, the voltage can be raised to a voltage higher than the voltage 11.