To enable keeping of packaged bodies in a small space and deformation from a plane form to a three-domensional form in a single action, by folding a shock-absorbing plate provided with a plurality of folding auxiliary lines to form a flat plate and fixing at least a part of the folded part and the shock- absorbing plate body so as to superpose them on the same plane.

The right and left ends 17, 18 of a corrugated cardboard 11 provided with ruled lines, notches, and cut lines in accordance with the shape of an article, are folded at the ruled line 13a so as to be superposed near the center line 12, and the surface of the folded part of the corrugated cardboard and the surface of the corrugated cardboard body 11a are folded so as to be superposed with each other out the same plane. Both ends 17, 18 of the folded corrugated cardboard 11 are fixed to the corrugated cardboard body 11a forming the shock-absorbing plate body by an adhesive to form a plane form packaged body 19. When assembling it, the upper face 20 of the plane form packaged body 19 is raised to the direction A, by only pushing the ruled line 13a to the direction of the center line 12 and a three-dimensional packaged body can be formed in a single motion.