To provide a technique effective for accurately detecting the mode of collision of a vehicle by using a pressure sensor.

This occupant restraint system 100 mounted on the vehicle includes a door beam 38 disposed in a sectioning region 33 sectioned by a door outer panel 31 and a door inner panel 32 of a vehicle door 30 to be displaced according to deformation of the door outer panel 31 during a vehicle collision, a cylindrical member 130 disposed in the sectioning region 33 to be compressed by the door beam 38 during the displacement of the door beam 38, a sealed space part 133 provided in the cylindrical member 130, the pressure sensor 120 for detecting pressure fluctuation of the space part 133, a deriving part 131 for deriving displacement amount and displacement speed of the door beam 38 based on the pressure fluctuation detected by the pressure sensor 120, and a deciding part 132 for deciding the collision type of the vehicle based on the displacement amount and displacement speed of the door beam 38 derived in the deriving part 131.

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