A wireless IC tag mounted on a low magnetic permeability material is mounted on a holding part which has first and second surfaces and is made of a high magnetic permeability material. The holding part has a penetrating part which penetrates the first and second surfaces, and a notch which penetrates a part of the first and second surfaces at a periphery. A discontinuous region is formed on the holding part due to the notch, and at least on the penetrating part, the wireless IC tag is tightly held together with the low magnetic permeability material. An axis of reverse direction magnetic flux generated by an eddy current that flows in the periphery of the penetrating part and the notch is shifted from an axis of the magnetic flux produced by electromagnetic waves directed toward the wireless IC tag on the first and second surfaces.