A robot system includes a speech recognition unit for converting speech information into text information, and a database retrieval unit for extracting a keyword included in the text information from a database. By designating a plurality of basic actions on a speech basis, and storing an action record, a combined action formed by combining the plurality of basic actions in time-series order can be named as a new action only in voice-based interaction. A user can designate complicated continuous actions by using only one word, and can easily have a conversation with the robot.