2. The document reading apparatus according to claim 1 , wherein the topic relation presenting device presents the description parts taken out side by side.
2. The document reading apparatus according to claim 1 , wherein the topic relation presenting device presents the description parts taken out side by side. 6. The document reading apparatus according to claim 2 , wherein the topic relation presenting device presents a plurality of thematic hierarchies corresponding to the plurality of documents and a correspondence relationship between the plurality of thematic hierarchies based on the plurality of common topics in a drawing, and presents a designated part of the plurality of documents in accordance with an instruction from the user given on the drawing.