<p>A resin overcap provided with an IC tag is to be used as an overcap to cover a metal cap and has the IC tag so as to prevent signal transmission and reception from being disturbed due to the metal cap. A resin overcap (20) to be used over a metal cap (50) is composed of a top panel (21) and a cylindrical side wall (23) to have the metal cap (50) fitted inside. On an upper portion on the inner surface of the cylindrical side wall (23), a step (25) or a protrusion (30) is formed for preventing the metal cap (50) fitted inside the cylindrical side wall (23) from moving upward. On the top panel (21), an IC tag (10) provided with the IC chip (5) is mounted such that a predetermined distance (D) is kept between a top plate (51) of the metal cap (50) fitted inside the cylindrical side wall (23) and the IC tag.</p>
