A vehicle driving assist system is configured to convey a risk potential relating to a preceding obstacle to a driver using both visual information and haptic information. For example, the vehicle driving assist system executes accelerator pedal actuation reaction force control such that an actuation reaction force is generated in accordance with a risk potential that expresses a degree of convergence between the host vehicle and a preceding obstacle. In order to convey to the driver in a clear manner which preceding obstacle(s) is an obstacle targeted by the risk potential calculation and the reaction force control, the system displays a reference frame or marker at a position corresponding to the targeted obstacle (preceding vehicle). At least one of size, color, shape and brightness of the marker is set in accordance with the risk potential.