A dialogue system that provides a driver with driving advice includes driving performance evaluation means for evaluating a driving performance of the driver estimated based on driving performance information using a normative driving performance as a reference; response evaluation means for evaluating a driver's response to the provided driving advice based on a change in the driving performance of the driver after provision of the driving advice; and output control means for adjusting contents of the driving advice provided to the driver based on the result of evaluation of the driving performance of the driver and setting a mode of expressing the driving advice based on the result of evaluation of the driver's response to the provided driving advice.
