Provided are an exterior body and an abnormality detector capable of suppressing bulking even when a heat generation detection function is provided. The exterior body of an electronic device generates heat during operation and is characterized by being provided with a magnetic body that is at least a portion of the exterior body, that has spontaneous magnetization, and that generates an electromotive force by exhibiting an abnormal Nernst effect through heat generation of the electronic device, wherein an electrode for extracting power is provided to the magnetic body.