To provide an authentication information input apparatus and an authentication information input method allowed to be utilized for authentication whose security function is improved by using an RFID card having a simple structure.

From an RFID card including a plurality of RFID tags, RFID tag ID information for uniquely specifying each of the plurality of RFID tags is read. An authentication information element stored in an authentication information storing file in which the RFID tag ID information and an authentication information element composing authentication information are correspondingly stored, based on the read RFID tag ID information, is retrieved. A difference between the authentication information element stored in the authentication information storing file and the retrieved authentication information element is extracted. By repeating reading, retrieval and extraction by the predetermined number of times, authentication information comprising the authentication information element extracted repeatedly is created, and the created authentication information is input to an authentication apparatus.

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