<p>Provided is a PTC device that more quickly detects the risk of a substrate reaching an abnormally high temperature and is therefore more effective in preventing an abnormally high temperature. A PTC device (10) comprises a layered support (14) that functions as a heat-transmitting medium and a polymer PTC element (12) disposed on top of the support (14). The polymer PTC element (12) is disposed (in a thermally connected state) on one surface (15) of the layered support (14), and the element (12) and layered support (14) are molded in resin such that the other surfaces (15') of the layered support (14) is exposed.</p>