A semiconductor integrated circuit device for use in a data communication apparatus includes setting means for setting, for each of a plurality of files that the semiconductor integrated circuit device manages, a flag indicating whether definition information functioning as information on each of the plurality of files is browsable or not browsable; and response sending means for sending, when provision of the definition information on a file is externally requested, a response falsely indicating that the semiconductor integrated circuit device is not managing the file existing in the plurality of files according to the flag set for the file indicating that the definition information on the file is not browsable.