An antenna device according to an exemplary embodiment includes a first metal layer, a first dielectric layer, a second metal layer, and a second dielectric layer. The first dielectric layer has a thermal conductivity and heat resistance that are higher than those of an FR-4 resin. The antenna device includes a first metal terminal and a second metal terminal, and a thermosensor. A pair of an input terminal and an output terminal of the thermosensor are electrically connected to the first metal terminal and the second metal terminal, respectively, and the second metal layer includes a first segment and a second segment. The first metal terminal is disposed above the first segment, and the second metal terminal is disposed above the second segment.