PURPOSE: To store a measurement date and the measured result to detect the transition of a bodily temperature by including a storage means where the output of a temperature measuring circuit and the output of a time counting means are stored with a timing signal which is generated from a timer means before a power source is turned off, the first and the second switch means, and a display means.

CONSTITUTION: When a prescribed time elapses after the start of temperature measurement, a signal which turns off the power source of a temperature measuring circuit 2 is generated from a timer circuit 4 for the purpose of preventing the consumption of a battery, and the power supply to the temperature measuring circuit 2 is cut off. Just before the power source of the temperature measuring circuit 2 is turned off, the measured result from the temperature measuring circuit 2 and data of a date, hours, and minutes of a time counting circuit 3 are stored in a storage circuit 5 by a storage signal generated from the timer circuit 4. The storage circuit 5 has four storage areas A, B, C, and D to store measured results and data of date, hours, and minutes in four past measurements, and the transition of the bodily temperature is stored with respect to four measurements in a day. They can be displayed on a display device 9 by the operation of a stored contents reading switch 11.