An antenna device includes a core, a terminal mounting unit, a coil, a plurality of elongated terminals, and an electronic component provided on the terminal mounting unit. The core is formed from a magnetic material. The terminal mounting unit is arranged adjacent to one side of the core. The coil, which is a wound conductive wire, is arranged on an outer circumference of the core. A sidewall of the terminal mounting unit includes a plurality of through holes into which the elongated terminals are inserted.