A data converting device which includes an input device which receives input information containing one or more kinds of data, a data analyzer which checks each kind of data constituting the input information and extracts data from the input information when the checked data are judged to be predetermined conversion target data to be subjected to a data conversion processing, and a controller which performs the conversion processing on an amount of the extracted data in accordance with a predetermined regulation for the kind of data. The invention further includes an information constructing device which replaces the non-converted data of the input information which converted extracted data, thereby reconstructing the input information, and an output device which outputs the reconstructed input information.