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Requirements for the use of IC tags on metallic objects have increased recently as systems that use IC tags have become widely adopted. We have proposed and designed a structure for an IC tag that operates on metallic objects. The structure of the IC tag consists of a conductive metal sheet at the bottom and a thin magnetic core made of a high-permeability composite sheet, which is inserted between the receiver coil and the metal sheet. With this structure, magnetic coupling between the antenna coil and the receiver coil is enhanced; furthermore, the influence of the metallic body to which an IC tag is attached is well suppressed. The method used to fabricate magnetic powders for the composite sheet is investigated together with the effect of the rolling process used to make a sheet on the magnetic anisotropy induced in the sheet. The permeability and quality factor are characterized for five samples in the frequency range from 10MHz to 1000MHz. The best fabrication method for magnetic composite sheets is to use 0.8〜1μm size Co powders as magnetic powder material to be mixed with a resin at the weight ratio between 70w% and 86w%, and to apply rolling after extrusion or pulling out after extrusion for a making sheet.