A vehicle driving assist system comprises a condition recognition device that detects a vehicle condition and a traveling environment around a subject vehicle; a reactive force application device that applies a reactive force, in conformance to the vehicle condition and the travelling environment around the subject vehicle, to an operation device; a condition change detection device that detects a condition change occurring around the subject vehicle; and a reactive force variation device that adjusts the reactive force applied by the reactive force application device in a period of time, when the condition change detection device detects that a condition around the subject vehicle has changed discontinuously.