In fully autonomous vehicles, occupants do not need to keep their eyes forward during driving and they are able to sit on any position, from a forward-facing position to a backward-facing. However, traditional passive safety systems such as seat belts, airbags, and air curtains have been developed only for the driver or passengers sitting on forward facing seats. In this paper, we propose a pre-crash safety system for an occupant sitting on a backward facing seat in front-end crashes. The proposed safety system starts to move the seat horizontally and tilt the seatback prior to a front-end collision to reduce crash force which may cause whiplash injury. The simulated results show a remarkable improvement in reduction of crashing force impact on occupant's whiplash injury using Honda Accord models posted on National Highway Traffic Safety Administration (NHTSA) and the hybrid III dummies with MADYMO 7.6 simulator.