First and second reference-potential generator units output first and second reference potentials V1 and V7, respectively, which correspond to first and second specific temperatures to be detected. An intermediate-potentials generator unit divides the potential difference between the reference potential V1 and the reference potential V7 to output intermediate potentials through nodes N2 to N6. A temperature-dependant-potential generator unit outputs the forward voltage drop of a diode which varies depending on the ambient temperature. A comparator compares one of the potentials of nodes N1 to N7 selected by a selector against the potential output by the temperature-dependant-potential generator unit and outputs the result of the comparison indicating the range of the ambient temperature.