While driving a vehicle, the driver often becomes irritated worrying about, for example, a meeting time or time of arrival at a destination. Although it varies from person to person, the driver tends to become irritated without noticing and such irritation generally has adverse effects on driving. For example, patent document 1 discloses a device that determines whether the driver is irritated and calms down the driver if he/she is irritated. The disclosed device detects the moving distance and the number of movements of the driver using a temperature sensor, determines that the driver is irritated if the moving distance or the number of movements exceeds a threshold, and calms down the driver by playing music or emitting a fragrance.
Thus, the device disclosed in patent document 1 determines whether the driver is irritated by detecting physical movements of the driver using the temperature sensor. However, it may become difficult to detect the temperature of the driver if the ambient temperature becomes high.
Meanwhile, psychological and physical condition of the driver starts affecting the driver before the driver starts driving and cause actual problems during driving. However, no technology has been proposed to detect the psychological and physical condition of the driver before the driver starts driving. Thus, with related-art technologies, it is not possible to detect the psychological and physical condition of the driver before the driver starts driving and therefore it is difficult to provide appropriate driving assistance in time.    [Patent document 1] Japanese Patent Application Publication No. 2004-106716