Abstract: There is provided a method for displaying the classification of a patent document to which multi-viewpoint patent classifications are added. The method makes it possible to grasp the patent document from a variety of viewpoints more than those obtained from the “Abstract” of the patent document without reading the specification, and hence improve the efficiency of patent research. The method comprises the steps of: (a) retrieving multi-viewpoint patent classifications added to the patent document; (b) using a database storing a multi-viewpoint patent classification table to read out multi-viewpoint patent classifications higher in hierarchy than each of the multi-viewpoint patent classifications retrieved; and (c) displaying, together with their titles, at least either the multi-viewpoint patent classifications retrieved or the higher levels of hierarchy.