DEVICE AND METHOD FOR PROTECTING PERSON ON BOARD

PROBLEM TO BE SOLVED: To prevent a shock relief system from being activated by a slight collision, and to achieve the early shut-off of a power supply to a heavy electric component in a vehicle at a vehicle collision.SOLUTION: A device for protecting a person on board includes an early shut-off heavy electric component 3, a secondary battery 5 serving as a power source, a shock relief system 6 such as an airbag system, a G sensor 1 serving as an acceleration detecting means, and a control unit 2. The control unit 2 uses an acceleration detected value α from the G sensor 1, a first threshold α1 for activating the shock relief system 6, and a second threshold α2 which is smaller than the first threshold α1 to determine a magnitude of the collision. Furthermore, when the acceleration detected value α is determined to be higher than the second threshold α2 and lower than the first threshold α1, the power supply from the secondary battery 5 to the early shut-off heavy electric component 3 is shut off without activating the shock relief system 6.