Disclosed are a document ranking system and method based on contribution scoring. The document ranking system includes: a content score calculating unit for calculating content scores for documents with respect to at least one word contained in the documents, with regard to each such word; a contribution score calculating unit for calculating contribution scores for the documents with respect to jointly occurring words; and a ranking unit for ranking the documents with respect to the at least one word, with regard to each such word, by using the content scores and the contribution scores.