To provide a temperature hysteresis sensor suitable or an automatic management device comprising a simple and low-cost mechanical structure which can be reset for reuse.

There are provided a base stage 1a, a heat expansion body 4 installed on the base stage, and a detecting part 16 which detects that the heat expansion body is expanded and displaced. The detecting part protrudes from the base stage when it detects displacement of the heat expansion body and keeps the protruded state while resettable to a position where it does not protrude from the base stage when the heat expansion body restores to such state as before displacement.