1. A keyword extracting device, comprising: an audio input section that inputs speech sound of speakers; a speech segment determination section that determines a speech segment for each speaker in connection with the input speech sound; a speech recognition section that recognizes the speech sound of the determined speech segment for each speaker; a speech response feature extraction section that extracts a feature of a speech response suggesting presence of a keyword on the basis of a response from another speaker to the speech sound of each speaker; and a keyword extraction section that extracts the keyword from the speech sound of the speech segment specified on the basis of the feature of the extracted speech response.