PROBLEM TO BE SOLVED: To provide a deep part thermometer capable of measuring an accurate deep part body temperature without enlarging an outside diameter.SOLUTION: A first temperature sensor T1/a third temperature T3 and a second temperature sensor T2/a fourth temperature sensor T4 are provided on both surfaces of a first heat resistance plate 22a and a second heat resistance plate 22b which are different in heat resistance in a thickness direction, respectively. The peripheral side surfaces of the first heat resistance plate 22a and the second heat resistance plate 22b are covered with a low emissivity material (aluminum plate) 23. Preferably, the surfaces of outside air sides of the first heat resistance plate 22a and the second heat resistance plate 22b are also covered with the low emissivity material 23. A frequency at which the heat introduced into the thermometer from an object to be measured is emitted is reduced, and a deep part temperature can be measured with higher accuracy even by a thermometer having a small diameter.
