A control unit of a communication device decrypts, when receiving via an antenna from a reader/writer a cipher key encrypted with a key same as a common key recorded in a recording unit by the reader/writer, the encrypted cipher key with the common key recorded in the recording unit, and when receiving via the antenna from the reader/writer a readout target address specifying a region of a data readout source in the recording unit encrypted with a cipher key same as the cipher key by the reader/writer, decrypting the encrypted readout target address with the cipher key, and transmitting the data recorded in the region specified by the readout target address obtained through decryption of the regions of the recording unit to the reader/writer via the antenna.