A Japanese proofreading apparatus has a correction history corpus, a proofreading candidate generation unit, a proofreading availability determination unit, and an automatic proofreading unit. The correction history corpus stores negative sentences as post-proofreading sentences and positive example sentences as post-proofreading sentences, in association with each other. The proofreading candidate generation unit acquires the post-proofreading sentences corresponding to the pre-proofreading sentences from the correction history corpus, according to characteristics of a proofreading target sentence. The proofreading availability determination unit selects, from the post-proofreading sentences acquired by the proofreading candidate generation unit, post-proofreading sentences with degrees of similarity between the proofreading target sentence and the post-proofreading sentences equal to or more than a predetermined threshold value, as proofreading candidates. The automatic proofreading unit proofreads the proofreading target sentence, using, out of the post-proofreading sentences selected by the proofreading availability determination unit, a post-proofreading sentence with the highest degree of similarity.