PURPOSE: To provide a general-purpose method for preparing a structuralized knowledge data base from a data base in a table format with a ruled transformatmon procedure by giving irreducibly minimum definition for transformation.

CONSTITUTION: A data structuralizing definition statement defining the structure of the structuralized knowledge data base and the items of data required for preparing the structuralized knowledge data base is prepared, the required data are extracted from the table format data base of a transformation source according to the defined contents of the data structuralizing definition statement, and the hierarchy information of the structuralized knowledge data base to be prepared is prepared from the data extracted from the transformation source table format data base. Then, inter-hierarchy data are connected according to the hierarchy information, and the data extracted from the transformation source table format data base are structuralized.