A response generation device according to the present disclosure includes: an acquisition unit that acquires input information serving as a trigger for generating a response to a user; and a response generation unit that generates the response to the user by using related information related to the input information in a case where it is determined that the response to the user is not able to be generated on the basis of only the input information. For example, the acquisition unit acquires voice information uttered by the user as the input information.