To prevent violation of privacy conducted, based on a read unique identification.

When an individual user notifies a trader MTT of user's E-mail address, the user generates and notifies a notification-specific E-mail address, which is an encrypted combination of a partner-specific information and user own e-mail address (EKNI(MTT//××//square××)), the partner-specific information composed of the trader name MTT and its e-mail address. When MTT requests sending of an RFID, the user sends an MTT-specific RFID, and if a party other than MTT (for example, MEC) requests sending of an RFID, the user also sends the MTT-specific RFID according to operations. After MTT has leaked personal information linked with the MTT-specific RFID, if MEC, which has received the MTT-specific RFID, it retrieves and obtains the leaked personal information to send an e-mail 85 to the notification-specific e-mail address included in the personal information, the partner-specific information (MTT//××), which is obtained by decrypting the notification-specific e-mail address, will not agree with the sending source MEC, so that a revealing source and an obtainer of the personal information can be identified.