The present invention improves the communication characteristics of an inlay using an auxiliary antenna, while protecting the inlay from physical and mechanical external forces, shocks or the like, without being subjected to the constraints of a dipole antenna. To that end, the present invention has a configuration, including: an inlay having an IC chip and only a loop circuit antenna, on which the IC chip is mounted, and not including another antenna; a casing for accommodating the inlay therein; and a planar top cover covering one surface side of the casing. The top cover is formed of a prescribed metallic material and includes a cutout opening at least on one side. The inlay is disposed in the casing so as to be positioned inside the cutout. The top cover functions as an antenna of the inlay by being electrically connected to the inlay.