When it is determined that a driver is extremely-concentrating, a fragrance emitted by a relaxing air freshener is intermittently released by emitting. To quickly reduce the tension of the driver, a long fragrance emit period is set, while a short fragrance emit stopped period is set. When it is determined that the driver is randomly scanning, the amount of the relaxing air freshener discharged is smaller than that when the driver is extremely-concentrating, and a shorter fragrance emit period is set, while a longer fragrance emit stopped period is set. As a result, an aroma that is so faint that the driver may not notice is used to maintain the random scanning state, and further, a fragrance emitted by an awakening air freshener is emitted, as needed, near the nose of the driver.