Abstract: Digest screen display content deciding means selects display elements belonging to respective regions of a document based on display priorities of the display elements, which are obtained by digest screen display priority information creating means, and decides selected display elements as display content of a digest screen under a condition where a total display area does not exceed a required display area. A merging relationship among the regions is set based on layout information for the regions, created by digest screen region layout information creating means. Display content deciding means decides the display content of a detail screen based on the merging relationship among the regions, and creates a digest of the detail screen based on control information created by control information creating means. Moreover, digest screen display content changing means changes the display content of the digest screen in response to an operation of a user.