PURPOSE: To reduce a vertical acceleration to a collided vehicle by providing a side wall and a lower portion, disposing an internal core in a plurality of brittle containers positioned along an axis, and forming an annular space between the core and the side wall.

CONSTITUTION: An annular lip 14 is formed at the upper end of a container 12 having a peripheral side wall 13, a drain hole 16 is provided in a bottom panel 15 at the lower end of it, and a shoulder 18 is formed at the middle position of it. An annular flange 22 and a conical or a truncated conical upper portion 24 are provided on an insert 20, and the average inner diameter of the annular space formed between the insert 20 and the side wall 13 is set at least approx. 25% of an average outer diameter of that space. Also, a cover 26 is engaged with the lip 14 in order to tightly hold the cover 26 at a fixed position. In addition, sand is stored on a barrier 10 of the container 12 so as to dispose it in disk shape at a sand mass of 10% or less. Thus, a vertical acceleration to a collided vehicle can be reduced over a wide range of vehicle height, and a large sand block improves water drainage from the sand, and a tendency that the vehicle is accelerated as one lump during the collision can be reduced.