1. A document information display system for displaying information relevant to a plurality of documents on a screen, wherein a two-dimensional coordinate plane having a document or a sentence, and a document group, a document, a sentence, or a word plotted as an element on one axis and as an element on the other axis, respectively, is displayed; and a relevance degree between an element of the one axis and a corresponding element of the other axis is displayed at each point of the two-dimensional coordinate plane.