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.