The present invention provides improvement of operations providing annotation and layout for an HTML page file. In an example embodiment, a page acquisition module obtains page files from a web server, and an HTML file analysis module extracts tags and characteristic values related to the layout. A page group detection module employs layout tags and their characteristic values to group page files that have the same or a similar layout. When an annotation addition module adds an annotation to an arbitrary page file in the obtained layout group, the annotation is applied for another page file in the layout group. When the layout group is divided or layout groups are unified, a correction module for the function of distance calculation corrects a calculation expression for a distance between pages or layout groups in order to reflect the division or unification results obtained by the user.