11. The storage medium according to claim 4 , wherein the evaluation pair analysis step has a document obtaining step of searching the document ID added to the evaluation pair composed of the specified object and the evaluation expression from the database and obtaining a document corresponding to the document ID; and a co-occurring term analysis step of extracting a phrase other than the object contained in the obtained document, counting the appearing number of the phrase, and extracting the phrase having a large appearing number as a co-occurring term which serves as a cause or a reason of the evaluation expression of the object.
4. The storage medium according to claim 1 , wherein in the evaluation pair extraction step, as extension information, a document ID, an evaluation expression ID, a network address including URL, a type of the object whether the object is a unique noun or a general noun are further added to the evaluation pair in which the object and the evaluation pair are combined.