A vehicle-mounted antenna device includes a base, a board, a circuit section, and a housing. The base is mountable on a roof of a vehicle. The board has an antenna element section and is stood on a surface of the base. The circuit section serves as at least part of a wireless communication circuit electrically connected to the antenna element section. The housing is made of a resin material and forms a projection of a vehicle outer shape. The board and the circuit section are located in space formed by the base and the housing. The board is stood on the surface of the base so that a first direction perpendicular to the surface of the base differs from a second direction equal to a thickness direction of the board. The circuit section implemented on the board at a position away from the base in the first direction.