An actuator of an active headrest apparatus for a vehicle, which is operably connected to a headrest assembly and selectively allows a headrest of the headrest assembly to pop out forwards when a vehicle collision occurs, may include a housing installed on a seatback frame and formed with a guide groove, an operating plate elastically supported over the housing, an operating bracket arranged between the housing and the operating plate and having a guide projection slidably inserted into the guide groove of the housing, and an operating wire unit connecting the operating bracket with the headrest assembly, wherein the operating wire unit includes an operating wire and an operating wire retainer to slidably receive the operating wire therein.