1 ) An information processing apparatus that classifies a plurality of document components contained in document information, into a plurality of groups, the apparatus comprising: a component converting section that converts each of said plurality of document components in said document information into element identifying information indicating the type or role of the document component; an intra-document pattern of sequence converting section that processes said document information converted by said component converting section to convert each of said sets of pieces of element identifying information that appear repeatedly at a predetermined threshold frequency or higher, into said element identifying information indicating a pattern of sequence of the set of the element identifying information; and a group classifying section that processes document information obtained by allowing said intra-document pattern of sequence converting section to convert said document information repeatedly, to group a plurality of said document components converted into a corresponding piece of element identifing information by said intra-document pattern of sequence converting section.