PURPOSE: To confirm temperature data, by storing the temperature data together with the time when the data is necessary or numerals of specific-interval time, and accessing them in time series with an external switch.

CONSTITUTION: A temperature sensor 20 senses temperature to generate a signal of frequency corresponding to the temperature, and the signal is inputted to a center counter 22 through an AND gate 23 only for a time based upon the control of a counter 21. A data processing circuit 24 converts the counting contents of the sensor counter 22 into a corresponding numeral, which is displayed at a display part A and also stored in a storage circuit 32 through a switch circuit controlled by a timer counter together with the time. When its contents are accessed and displayed, the external switch 34 is operated to connect a time counter 12 and the data processing circuit 24 together through a line.