PURPOSE: To allow even a word of polysemy to correspond to a correct concept and to automatically prepare concept relation much more than the number of word pairs.

CONSTITUTION: Inter-word relation data 22 are read out and allowed to correspond to concepts stored in a thesaurus 21. When the data 22 correspond to one concept, a pair of the concept and a verb is registered in a single concept table 23, and when the concept making a pair with the verb has been already registered in the table 23 and the concept concerned and the registered one have master-slave relation in the thesaurus 21, a cencept between both the concepts and registered verb are registered in the table 23 as a new pair. When data 22 correspond to plural concepts, a pair of the concepts and the verb is registered in a plural concept table 24, a concept having the shortest distance in the thesaurus 21 from the concept making a pair with the verb out of a master or slave concept in these concepts is selected and a pair of the selected concept and the verb is registered in a concept relation dictionary 25 as a new pair.