An antenna unit includes a substrate, a body that includes a first conductive portion and a second conductive portion opposed to each other on side surfaces orthogonal or substantially orthogonal to a first main surface of the substrate, and first and second coil antennas the winding axes of which are orthogonal or substantially orthogonal to the first main surface. In a plan view of the first main surface, the first coil antenna is positioned in proximity to the first conductive portion, compared with the second coil antenna, and the second coil antenna is positioned in proximity to the second conductive portion, compared with the first coil antenna. In a plan view of the first main surface, a straight line passing through the first coil antenna and the second coil antenna intersects with the first conductive portion and the second conductive portion.