A reader/writer apparatus includes a tag search instruction receiving unit that receives a tag search instruction from a host apparatus. The tag search instruction includes a data read instruction and/or a data write instruction on the RFID tag. The reader/writer apparatus also includes a tag identification information requesting unit that transmits to the RFID tag a request for transmission of tag identification information uniquely identifying the RFID tag when the tag search instruction receiving unit receives the tag search instruction; and a data processing requesting unit that transmits a data read request and/or a data write request to the RFID tag identified by the tag identification information based on the read instruction and/or the write instruction when receiving the tag identification information transmitted from the RFID tag in response to the request for transmission transmitted from the tag identification information requesting unit.