A diode type ultraviolet sensor having a layered-structure body including a conductive layer composed of a sintered ceramic body having conductivity and a semiconductor layer composed of an oxide semiconductor including ZnO. The semiconductor layer is disposed on a principal surface of the conductive layer and forms a heterojunction with the conductive layer. The ultraviolet sensor is used in such a condition that the semiconductor layer is positioned at a light-receiving side irradiated by ultraviolet rays. The semiconductor layer is preferably composed of a sintered body. The sintered body serving as the conductive layer and sintered body serving as the semiconductor layer are preferably formed by co-firing. Terminal electrodes are provided on a principal surface and the other principal surface of the layered-structure body, respectively.