An insulating substrate including a principal surface and coil antennas disposed on the substrate and each including a coil conductor. The coil conductor includes a winding axis in a direction parallel or substantially parallel to the principal surface of the substrate. An auxiliary loop conductor that is connected to the coil conductors of the coil antennas and generates a magnetic flux that is in phase with those of the coil antennas as seen from the direction of the winding axis of the coil conductor is provided in and on the substrate.