A wireless IC device includes a substantially rectangular parallelepiped dielectric body, a metal pattern that is provided on the surface of the dielectric body via a film and functions as a radiator, and a wireless IC element coupled to feeding portions of the metal pattern. The dielectric body has a laminated structure including a folded flexible dielectric layer. Surfaces of the dielectric layer which face each other after the dielectric layer has been folded are non-bonded surfaces.