An antenna device configured to be attached to a vehicle includes: an antenna of a resonance type; and a matching circuit connected to the antenna, wherein the matching circuit includes a first matching circuit connected to a feeding portion of the antenna and a second matching circuit connected to a subsequent stage of the first matching circuit, wherein the first matching circuit reduces an impedance in a frequency band that is away to a higher-frequency range or a lower-frequency range from a resonance point of the antenna such that the impedance is lower than before connection of the first matching circuit, and the second matching circuit increases an impedance in a vicinity of the resonance point of the antenna such that the impedance is higher than before connection of the second matching circuit.