PURPOSE: To prevent an article from erroneously being put by rewriting a taken out word to the declined form of a retrieved noun or the noun phrase where the article is put before the noun.

CONSTITUTION: In a dictionary 13, the declined form of each noun is stored, and the declined form of a noun where an article can be put and the declined form of a noun where the article is necessary is stored in a state that the article is put before the declined form. A retrieval means 14 receives a word from a word discimination means 12 by a conversion operation, retrieves the dictionary 13, takes out the declined form of the noun matching with the word and outputs the form to a display means 15. When the conversion operation is performed again, the retrieval means 14 takes out the noun phrase stored after the declined form one by one from the dictionary 13 and outputs the noun phrase to a display means 15 on the occasion. The display means 15 rewrites the word on the document memory 22 at the location that the word discimination means 12 stores to the received conjugated form and noun phrase at a point of time when the means 15 receives the declined form and the noun phrase that the retrieval means 14 outputs.