A wireless IC device includes a wireless IC chip; a feeder circuit board which has the wireless IC chip located thereon, is magnetically coupled to a radiation plate, supplies electric power to the wireless IC chip, and relays signals between the wireless IC chip and the radiation plate; and a substrate on which the feeder circuit board is placed. On the substrate, there are formed a plurality of positioning markers indicating the boundaries of a plurality of positioning areas in which the feeder circuit board is selectively placed.