Abstract: A dialogue system which correctly identifies an utterance directed to a dialogue system by using various pieces of information including information other than a voice recognition result without requiring a special signal is provided. A dialogue system includes an utterance detection/voice recognition unit that detects an utterance and recognizes a voice and an utterance feature extraction unit that extracts features of an utterance. The utterance feature extraction unit determines whether or not a target utterance is directed to the dialogue system based on features including a length of the target utterance, time relation between the target utterance and a previous utterance, and a system state.