DANGEROUS DRIVING WARNING DEVICE, DANGEROUS DRIVING WARNING SYSTEM, AND DANGEROUS DRIVING WARNING METHOD

A travel information sensor (14A) senses travel information of a host-vehicle. A biological information sensor (13A) senses biological information of a driver. A camera unit (12A) senses a facial expression of the driver. A communication unit (32A) acquires an agitating degree indicating a degree to which an other-vehicle agitates the driver of the host-vehicle, via a network (4). An agitated degree calculation unit (313A) calculates an agitated degree indicating a degree to which the driver of the host-vehicle is agitated by the other-vehicle. A danger degree determination unit (312A) determines a danger degree including whether the driver of the host-vehicle is agitated by the other-vehicle, based on the agitated degree and the agitating degree. A presentation unit (33A) warns the host-vehicle of the danger degree if it is determined that the driver of the host-vehicle is agitated by the other-vehicle.