A vehicle driving assist system has a controller configured to urge a driver to slow down (decelerate) in locations where visibility is poor. The controller detects a traveling condition of a host vehicle, e.g., when the host vehicle is approaching a designated area, such as a school zone, and then selectively executes an imaginary speed limiting road protrusion control that generates an imaginary speed limiting road protrusion by artificially reproducing a vehicle behavior that simulates the host vehicle crosses an actual speed limiting road protrusion arranged on a road surface, based on the traveling condition of the host vehicle.