DRIVER ASSISTANCE DEVICE, DRIVER ASSISTANCE METHOD, AND NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM STORING PROGRAM

A driver assistance device includes a processor. The processor is configured to: automatically decelerate an own vehicle in accordance with a relative relation between the own vehicle and a vehicle traveling ahead that is traveling forward of the own vehicle; change deceleration of the own vehicle by a first change amount, or a second change amount that is larger than the first change amount, when automatically decelerating the own vehicle; perform behavioral determination to estimate whether behavior of the own vehicle will become unstable when the own vehicle is automatically decelerated; and change the deceleration by the first change amount when automatically decelerating the own vehicle, when the behavior of the own vehicle is estimated to become unstable.