To make a sub-member deformed in prior to deformation of a main body member for forming a body skeleton, against an axis-directional input, even in low speed collision of relatively low damage, to say nothing of high speed collision.

Plastic deformation reaction of the sub-member 11 is made high in a rear part 11B compared with a front part 11A, and the plastic deformation reaction of the rear part 11B in the sub-member 11 is made lower than yield point reaction of the main body member 10. A yield point lowering mechanism 20 is provided to bring the yield point reaction of the main body member 10 into a level substantially same to the plastic deformation reaction when the rear part 11B of the sub-member 11 is deformed. A relation of Fsd>(αs/αb)>Fbd is satisfied in the low speed collision, and the deformation is brought from the sub-member to the main body member 10 in order, even in the low speed collision, where αb is a braking ratio of the sub-member 11, Fbd is the plastic deformation reaction in the high speed collision in the rear part 11B of the sub-member 11, αs is a braking ratio of the main body 10, and Fsd is the yield point reaction in the high speed collision.