A wireless IC device, comprising: an electromagnetic coupling module including opposed first and second main surfaces; and a radiation plate (2, 3) including a base material (21, 31), a first radiation electrode (22, 23) and a second radiation electrode, wherein the radiation plate is disposed on the electromagnetic coupling module such that the first radiation electrode (22, 23) is disposed on the first main surface of the electromagnetic coupling module, and such that the second radiation electrode is disposed on the second main surface of the electromagnetic coupling module, wherein the electromagnetic coupling module includes a feed circuit substrate, wherein the feed circuit substrate includes an inductance element, an upper coupling electrode, and a lower coupling electrode, and wherein the radiation plate is disposed on the electromagnetic coupling module such that the first radiation electrode (22, 23) is capacitively coupled with the upper coupling electrode of the feed circuit substrate, and such that the second radiation electrode is capacitively coupled with the lower coupling electrode of the feed circuit substrate, and the electromagnetic coupling module further includes a wireless IC mounted to the feed circuit substrate, the inductance element of the feed circuit substrate is coupled to the wireless IC, the feed circuit substrate comprises an uppermost dielectric layer, a lowermost dielectric layer and at least two further dielectric layers (41B-41F), the at least two further dielectric layers (41B-41F)are positioned in-between the uppermost dielectric layer and the lowermost dielectric layer, the wireless IC and the upper coupling electrode are provided on the uppermost dielectric layer, the lower coupling electrode is provided on the lowermost dielectric layer, inductor electrodes (45a-d, 46a-e, 47a-e) are formed on the at least two further dielectric layers (41B-41F), the inductor electrodes (45a-d, 46a-e, 47a-e) are connected to one another through via holes such as to form the inductance element, the inductance element is interconnected between the wireless IC and the upper and lower coupling electrodes (42, 43), and the feed circuit substrate includes a resonant circuit, the frequency of signals to be emitted from the first radiation electrode (22, 23) and the second radiation electrode being substantially determined on the basis of the self-resonant frequency of the resonant circuit. an electromagnetic coupling module including opposed first and second main surfaces; and a radiation plate (2, 3) including a base material (21, 31), a first radiation electrode (22, 23) and a second radiation electrode, wherein the radiation plate is disposed on the electromagnetic coupling module such that the first radiation electrode (22, 23) is disposed on the first main surface of the electromagnetic coupling module, and such that the second radiation electrode is disposed on the second main surface of the electromagnetic coupling module, wherein the electromagnetic coupling module includes a feed circuit substrate, wherein the feed circuit substrate includes an inductance element, an upper coupling electrode, and a lower coupling electrode, and wherein the radiation plate is disposed on the electromagnetic coupling module such that the first radiation electrode (22, 23) is capacitively coupled with the upper coupling electrode of the feed circuit substrate, and such that the second radiation electrode is capacitively coupled with the lower coupling electrode of the feed circuit substrate, and the electromagnetic coupling module further includes a wireless IC mounted to the feed circuit substrate, the inductance element of the feed circuit substrate is coupled to the wireless IC, the feed circuit substrate comprises an uppermost dielectric layer, a lowermost dielectric layer and at least two further dielectric layers (41B-41F), the at least two further dielectric layers (41B-41F)are positioned in-between the uppermost dielectric layer and the lowermost dielectric layer, the wireless IC and the upper coupling electrode are provided on the uppermost dielectric layer, the lower coupling electrode is provided on the lowermost dielectric layer, inductor electrodes (45a-d, 46a-e, 47a-e) are formed on the at least two further dielectric layers (41B-41F), the inductor electrodes (45a-d, 46a-e, 47a-e) are connected to one another through via holes such as to form the inductance element, the inductance element is interconnected between the wireless IC and the upper and lower coupling electrodes (42, 43), and the feed circuit substrate includes a resonant circuit, the frequency of signals to be emitted from the first radiation electrode (22, 23) and the second radiation electrode being substantially determined on the basis of the self-resonant frequency of the resonant circuit.