The invention discloses an arousal support system and an arousal support method. The arousal support system includes a dialogue processing unit configured to output a dialogue speech in a form of a question and obtain response speech which is a response of a driver to the dialogue speech; a response time measuring unit configured to measure a response time from outputting the dialogue speech by the dialogue processing unit till obtaining the response speech by the dialogue processing unit; a database storing the response time measured by the response time measuring unit; a statistic calculating unit configured to calculate a statistical value of the response time based on one or more response times stored in the database; and a first estimating unit configured to derive an estimated valueof wakefulness of the driver based on the response time measured by the response time measuring unit and the statistical value calculated by the statistic calculating unit.