A question answering system includes a question input unit input to a question, a search unit, an anaphoric analysis unit, an information extraction unit and an answer candidate extraction unit. The search unit executes search processing based on the input question. The anaphoric analysis unit executes anaphoric analysis processing on a search result. The information extraction unit extracts sentences, which include expressions having a reference relation therebetween, as reference relation sentences, the reference relation determined by finding relation in an expressions of at least one of a noun phrase, a pronoun, and a zero pronoun between sentences in the search result on a basis of a result of the anaphoric analysis; selects a first candidate sentence from a passage obtained as the search result; and selects a second candidate sentence, which is the reference relation sentence of the first candidate sentence. The answer candidate extraction unit extracts an answer candidate.
Question answering system, data search method, and computer program