Attribute mapping information is stored, in which a superclass of an associated class in an integration-source ontology already associated with an integration-destination ontology, an attribute of the superclass, and an integration destination attribute of a class in the integration destination are associated with each other. An integration target class in the integration source is specified to acquire an attribute of a superclass of the integration target class. An associated class having the shortest distance from the integration target class is specified, to specify an integration-destination-associated class associated with the specified associated class. An inheritance relation is followed from the integration-destination-associated class to specify a class having the integration destination attribute corresponding to the attribute in the mapping information as a position where the class associated with the integration target class is present.