PURPOSE: To offer a data base creating method capable of easily constituting a document like a document accumulation type data base only by working the document and highly utilizing the document like a relational data base.

CONSTITUTION: The data base creating method is constituted of a document reading step A for reading out a document attained by natural language, an analytical step B for analyzing the natural language in the read document and extracting words, a dividing step C for dividing the words extracted by the step B based upon a thesaurus dictionary and forming groups, and a formation step D for creating a data base by using the words extracted and divided by the steps B, C in accordance with knowledge structure to be the knowledge frame of the words including grammatical properties and dividing information.