PURPOSE: To make measurement of accurate atmospheric air temp. and bodily temp. possible by calculating the ambient temp. and bodily temp. with a CPU and a memory from the respective temperatures and temp. differences of plural temp. sensors.

CONSTITUTION: At the measurement mode of atmospheric air temp., the temp. measured with a temp. sensor 5 in contact with the atmospheric air, and the temp. measured with a temp. sensor 6 for removing the effect of bodily temp. are inputted to an A/D conversion part 11 by means of a change-over switch 10. The measurement data having been A/D converted are beforehand programed in a CPU12 and a memory 13. From the measurement data of the temp. sensors 5, 6, the true atmospheric air temp. is processed by the CPU12 according to the equations calculating said temp., and the results thereof are displayed in a digital display part 7. When the atmospheric air temp. is known with other thermometers or the like, that temp. is inputted by an input means 14 occasionally, by which the accurate correction is accomplished with the CPU and the memory 13. In the bodiy temp. measuring mode, too, the accurate bodily temp. is measured by using programs for calculating bodily temp. in the same manner.