PURPOSE: To make the edit and revision of a document efficient and simple by providing an input/output means talking an interface, a layer management means managing the document as a layer, a means storing the information of each layer and a control means controlling it.

CONSTITUTION: An input/output means 1 applies a language input interface such as a command and output of a document. A layer management means 2 manages information where a key such as a classification item or a key word corresponds to what kind of document or information where a sentence relates which key and groups sets of items in a layer so as to make them abstract. A control means 3 references the information of the layer management means 2 based on the request inputted from the input/output means 1, quotes the information stored in storage means 4W5 of the relevant layer and sends output information to the input/output means 1. Thus, the information is managed unifiedly.