PURPOSE: To eliminate wrong displaying of temp. by inhibiting the display of temp. for a specified time after starting of measuring temp.

CONSTITUTION: A microprocessor 3 executes a time display mode or a temp. measurement mode according to a switch state signal 6a. When a semiconductor switch 1b is closed in the temp. measurement mode, electric power is supplied from a power source 1c to a thermometer 1a, and temp. measurement is started. In this time, a pattern for displaying that the measurement is now under preparation is outputted to a display device 9. Upon lapse of a specified time, temp. is displayed on the display 9.