Impact energy absorber

The absorber (1) has an aggregate formed by lapping a kraft paper on an inner and outer side of a metal sheet e.g. a hard aluminum foil. The absorber is a flexible pipe with a circular cross-sectional shape with concave and convex portions in a spiral form on the surface. The energy is absorbed by plastic deformation in a radial direction of the absorber. The outside diameter of the absorber is 20 to 50 mm, the pitch of the portions is 1.4 to 2 mm, and vertical width of the portions is 2.3 to 3.2 mm.