An RFID tag having mounted thereon an IC chip capable of receiving and delivering information from and to an external source without contact. In the RFID tag, a central axis of its own antenna having mounted thereon the IC chip coincides with a center of the RFID tag, and an antenna width is controlled. That is, a position of the central axis of the antenna is controlled to correct the mass eccentricity of the RFID tag. Further, the RFID tag is an RFID tag having mounted thereon the IC chip capable of receiving and delivering information from and to an external source without contact, and an RFID tag having attached thereon the IC chip at a position in which a first and a second antenna lengths are different from each other.