A vehicle driving assist system comprises a travel situation detection device that detects a vehicle condition and a traveling environment around a subject vehicle; a risk potential calculation device that calculates a risk potential around the subject vehicle based upon detection results of the traveling situation detection device; an accelerator pedal reaction force calculation device that calculates an accelerator pedal reaction force command value based upon the risk potential which is calculated by the risk potential calculation device; an accelerator pedal reaction force generation device that generates an actuation reaction force for an accelerator pedal, according to the accelerator pedal reaction force command value which is calculated by the accelerator pedal reaction force calculation device; a driving intention detection device that detects a driving intention of an operator of the subject vehicle; and an accelerator pedal reaction force modification device that adjusts the actuation reaction force to be generated for the accelerator pedal, based upon a detection result of the driving intention detection device.