PURPOSE: To appropriately restrain a passenger while securing a space around feet of the passenger by providing a first movable protector for supporting nearly a leg part front side of the passenger and a second movable protector for supporting nearly a leg part rear side of the passenger.

CONSTITUTION: A seat cushion 21 of a seat 3 consists of a front part cusion 21a and a rear part cushion 21b being a second protector for supporting a thigh part. The front part cushion 21a is movable by means of a sliding device 25. This sliding device 25 is constituted so that extension and contraction of an air cylinder 35 may move a support frame 27 forward under guidance of a guide pin 33 of a seat frame 29 via a connecting member 31. A knee protector device 5 being a first protector is arranged under a dash board 44 and supported by a support 51 via a pair of air cylinders 47 and link brackets 49. The air cylinders 35, 47 are actuated via a controller 7 in the case where vehicle deceleration detected by a collision detecting sensor 73 exceeds a predetermined value.