Provided is a wireless IC device which is reduced in sizes without causing deterioration of radiation characteristics. The wireless IC device is provided with an electromagnetically coupled module (1) composed of a wireless IC chip (5) for processing transmission/reception signals and a feed circuit board (10) whereupon a feed circuit including an inductance element is arranged. The feed circuit board (10) is provided with an external electrode which is electromagnetically coupled with the feed circuit, and the external electrode is electrically connected to a shield case (28) or a wiring cable. The shield case (28) or the wiring cable functions as a radiation plate, the wireless IC chip (5) is operated by the signal received by the shield case (28) or the wireless cable, and a response signal from the wireless IC chip (5) is radiated to the external from the shield case (28) or the wiring cable. A metal component which functions as the radiation plate may be a ground electrode arranged on a printed wiring board (20).