A vehicle drive assistance system is provided, which includes a processor configured to execute a required driving ability estimating module to estimate a driver's driving ability required for driving a vehicle based on a traffic environment around the vehicle and drive assistance provided to the driver by the vehicle, a current driving ability estimating module to estimate a driver's current driving ability, and a changing module to reduce the required driving ability by performing reduction processing in which comprehension of the traffic environment by the driver is facilitated when the current driving ability is lower than the required driving ability.