A driving assistance system includes a stop assistance controller, an assistance necessity determining unit, and a determining position arithmetic unit. The stop assistance controller is configured to perform stop assistance of an own vehicle. The assistance necessity determining unit is configured to determine whether it is necessary to perform the stop assistance of the own vehicle based on a stop determining position where it is determined whether to perform the stop assistance of the own vehicle and a predicted display state of a traffic signal at a time the own vehicle arrives at the stop determining position. The determining position arithmetic unit is configured to determine the stop determining position according to a current display state of the traffic signal.