In this study, we attempted to develop a new head injury criterion which is evaluated by the hydrostatic pressure in the head crash accident. This pressure is mostly occurred in the pedestrian during a collision. Main subject of this study is to find the threshold value of the functional injury of the brain obtained by the impact experiment. We used the hydrostatic pressure as a criterion value by measuring PC-12 cultured nerve cell injury. PC-12 cultured nerve cell was employed to imitate the human's nerve cell. We observed cytoskeleton injury caused by the hydrostatic pressure loading. It reveals that the cytoskeleton injury depends on the hydrostatic pressure, and the injury threshold value was obtained. It was concluded that a new head injury criterion based on the nerve cell injury was established.
