An active headrest apparatus for a vehicle seat. A contact area in which the upper body of a person who is seated in a car in the event of a rear-end collision of the car is moved backward due to an inertial force and contacts a back plate can be increased, and a distance at which a headrest is moved and rises can be increased so that the function of an active headrest can be more faithfully performed and neck injury of the person who is seated in the car can be prevented to the maximum.