A vehicle travel assist device installed on a vehicle includes: a vehicle travel control device that controls travel of the vehicle; and a travel state acquisition device that acquires travel state information indicating a travel state of the vehicle. The vehicle travel control device: detects that a first wheel of the vehicle climbs over a difference-in-level, based on the travel state information; acquires a first driving force required for the first wheel to climb over the difference-in-level or a change in the travel state when the first wheel passes the difference-in-level, as reference information, based on the travel state information; estimates a second driving force required for a second wheel of the vehicle to climb over the difference-in-level, based on the reference information; and generates the estimated second driving force when the second wheel passes the difference-in-level after the first wheel.