To prevent a shock absorbing material mounted on a vehicle body from collapsing or being scattered under the shock at the time of a collision. The four sides of a shock absorbing material formed of a foamed material are surrounded by a bellows form cover consisting of four corrugated plates inclusive of corrugated plates. Under an external force due to collision, the bellows is folded and contracted easily, but is difficult to be deformed in the width directions. Therefore, the shock absorbing material receives the energy upon collision in its initial shape, so that the energy is absorbed substantially by the compression of the shock absorbing material. Accordingly, it suffices to design a set load for the shock absorbing material by taking into account only the shock absorbing material, so that it is easy to design the shape, material and the like of the shock absorbing material.