Abstract: A question answering system includes a question sentence analyzing unit, a question keyword identifying unit, a passage acquiring unit and an answer generating unit. The question sentence analyzing unit determines whether or not an input question sentence is an ambiguous question. The question keyword identifying unit extracts a question keyword from the input question sentence. The passage acquiring unit executes a search process to which the question keyword is applied. The answer generating unit generates answers in a form of a list of predicates extracted correspondingly to the question keyword, based on passages acquired by the passage acquiring unit.