A question answering system estimates an answer type of an answer from a input question statement, extracts keywords from the question statement and retrieves a document database, extracts language expressions (answer candidates) from the extracted document data, assigns evaluation points thereto. When there are a plurality of answer candidates having the same language expression, the system sorts those evaluation points in descending ranking order of evaluation, calculates values of evaluation points using such weighting that the value to be processed for each evaluation point diminishes, regards the sum total of those values as the evaluation point of the answer candidate, and outputs the answer candidate whose counted evaluation point is equal to or greater than a predetermined evaluation as an answer.