An inductive antenna device intervenes in communication between an RFID tag including an RFID chip and a tag antenna and an RFID access device for accessing the RFID tag. The inductive antenna device includes an access-device-side antenna that is electromagnetically coupled with the antenna of the RFID access device, and a tag-side antenna that is electromagnetically coupled with the tag antenna. The RFID chip and tag antenna in the RFID tag are in an electromagnetically shielded space. The inductive antenna device is attached to the RFID tag or the inductive antenna device is brought in a predetermined position to make communication possible between the RFID tag and RFID access device. An authorized access to the RFID tag is thereby permitted with easy operation with unlimited number of access times, and an illegal leak of the tag information is prevented with a low cost configuration.