To provide an overheat detecting and alarming device capable of detecting an abnormal overheat of an electric apparatus, etc., simply and surely, and capable of maintaining accurate detection ability for a long time.

This overheat detecting and alarming device is mounted directly or indirectly on an apparatus and detects an abnormal overheat of the apparatus exceeding a prescribed temperature to issue an alarm signal, It is equipped with an alarm material 1 for presenting an alarm state such as smell emanation or coloring in case of abnormal overheat of the apparatus, a sealed container 5 at least a part of which is made of inorganic thin film 6 and the interior of which is filled with the material 1, and a sealed container breaking means 2 for detecting the overheat of the apparatus exceeding the prescribed temperature by a temperature rise of itself exceeding a prescribed temperature and breaking a part of the film 6 of the container 5 by a change in its shape attending on the temperature rise exceeding the prescribed temperature to bring the material 1 into the alarm state.