A document processing system includes a unique information acquiring section, a similar document element selecting section and a replacement document data acquiring section. The unique information acquiring section acquires unique information to be recorded. The similar document element selecting section selects one similar document element corresponding to the unique information from each of one or a plurality of groups of similar document elements. The one or the plurality of groups of similar document elements relate to one or a plurality of document elements respectively. The one or the plurality of document elements is contained in document data. The replacement document data acquiring section acquires replacement document data which is generated by replacing the document elements with the respective similar document elements selected by the similar document element selecting section.