An RFID tag unit is constituted of a seal member part, a substrate material part layered on the seal member part, and a print member part layered on the substrate material part. An RFID tag that comprises an LSI chip, an antenna and an impedance adjustment part is formed on the surface of the substrate material part. Of the seal member part and substrate material part, a part positioned under the impedance adjustment part is cut off, and an impedance adjustment part cutoff part is equipped in the cutoff area. Cutting the impedance adjustment part cutoff part off the RFID tag unit cuts the impedance adjustment part, which has been connected to the antenna, from the RFID tag.