Information related to voice of a question and information related to voice of a response to the question are received. An analysis section acquires a representative pitch of the question (e.g., a pitch of the end of the question), and a representative pitch of the response (e.g., an average pitch of the response) based on the received information. On the basis of comparison between the representative pitch of the question and the representative pitch of the response, an evaluation section evaluates the voice of the response to the question on the basis of how much a difference between the respective representative pitches of the question and the response is away from a predetermined reference value (e.g., a fifth consonant interval). Further, a conversation interval detection section is provided for detecting a conversation interval, i.e., a time interval from the end of the question to the start of the response.