DRIVING ASSISTANCE SYSTEM AND DRIVING ASSISTANCE METHOD

A driver assistance device, a driver assistance method, and a driver assistance system according to the present invention make it possible to: determine a departure risk of a vehicle departing from a drivable width of a road on which the vehicle travels, based on a driving environment ahead of the vehicle; determine, based on the departure risk, actuator operation variable-related information regarding an operation variable of an actuator related to a steering and/or braking/driving operation that causes the vehicle to travel along the target trajectory; and output the actuator operation variable-related information to the actuator. This allows for control that ensures stability of the vehicle and prevents lane departure of the vehicle in a compatible manner.