To ensure a sufficient communication distance and to concurrently suppress a conductor loss, a coil antenna includes a magnetic core including a first peripheral surface including at least a first principal surface, a first coil conductor located on the first principal surface and wound around a predetermined winding axis, a first base material layer stacked on the first principal surface, including at least a first surface parallel or substantially parallel to the first principal surface, and made of a material having a lower magnetic permeability than the magnetic core, and a second coil conductor located on at least the first surface. Opposite ends of the second coil conductor are coupled to the first coil conductor on the first principal surface, and a direction in which a current flows through the first coil conductor on the first principal surface is substantially the same as a direction in which a current flows through the second coil conductor on the first surface.