In a safety device for the occupant of the central rear seat position in a motor vehicle the arm-rest present between the front seats is used for his or her effective protection in the case of a frontal collision. A pivoting drive, which engages the arm-rest, pivots the arm-rest out of its position extending approximately horizontally in the longitudinal direction of the vehicle towards the front seat back-rest in the case of a crash. The pivoting drive is connected to a sensor which detects a vehicle deceleration, and which trips the pivoting drive to erect the arm-rest when a prescribed value of the integrated vehicle deceleration is exceeded.