PURPOSE: To easily correct errors in measured temperatures.

CONSTITUTION: A temperature measuring instrument is provided with a temperature measuring voltage generating section 50 which uses a resistance temperature detector R1 and generates the temperature measuring voltage V1 corresponding to the variation of the resistance value of the detector R1, reference voltage generating section 52 which generates a reference voltage V0, A/D converter 54 which A/D-converts the voltages V0 and V1 and outputs the ratio V1/V0 between the reference voltage V0 and temperature measuring voltage V1, and measured temperature outputting section 10 for measuring the temperature Mt corresponding to the ratio V1/V0. The instrument is also provided with a set temperature inputting section 12 through which the operator of this instrument, etc., inputs the set temperature St corresponding to the correct temperature of the detector R1. The measured temperature outputting section 10 has a function which corrects the measured temperature Mt based on the set temperature St.