An antenna device includes first and second coil antennas with winding axis directions that are not perpendicular to each other, and a feeder coil including a winding axis that extends perpendicular or substantially perpendicular to the winding axis of the first coil antenna. The feeder coil is located between the first and second coil antennas in the winding axis direction thereof. A first coil aperture is closer to a coil aperture of the first coil antenna than a second coil aperture. The second coil aperture is closer to a coil aperture of the second coil antenna than the first coil aperture. The first and second coil antennas are connected to each other in a polarity such that magnetic fluxes thereof with respect to the winding axis direction of the first coil antenna are in phase with each other.