To keep a shape of corrugation without damaging the cardboard when the shock absorbing material is manufactured in a shock absorbing material applied with prior art cardboard.

This cardboard comprises at least a front liner, a corrugating medium and a rear liner. Since this cardboard is constituted so that the corrugations are formed in a direction perpendicular to the corrugations of the corrugating medium under a state in which the medium is crushed flat, the cardboard is not damaged when the shock absorbing material is manufactured, and the corrugations of the cardboard do not restore their original state and the shape of the corrugations is maintained, resulting in that the shock absorbing material can keep an action of the shock absorbing material.