PURPOSE: To improve operability and reliability, by the constitution, wherein a thermoelectric conversion element is arranged at one end of an electronic clinical thermometer, an input switch is arranged at the other end, and the input switch is operated by the compression into the longitudinal direction of the electronic clinical thermometer.

CONSTITUTION: A movement block 52 of an electronic clinical thermometer is constituted in a slender rod shape as a whole. With a circuit substrate as a center, a thermoelectric conversion element is arranged at one end of the thermometer, and an input swich button 51 is arranged at the other end. The input switch button 51 is operated by the compression into the longitudinal direction of the electronic thermometer. The switch stroke is set so that it is slightly larger than the protruding amount of the switch botton from a back lid. A cap surface is attached to the back lid. Thus, a erroneous-input preventing performance is improved without impairing the ease of compression, and operability and reliability can be improved.