To form a cardboard shock-absorbing material of which assembling can be easily carried out and having a strength against shock.

Side plates 2 are cooperatively arranged around a bottom plate 1. Corner pieces 4 are connected to the adjoining side plates through diagonal folding lines 3 of 45°. Two leg plates 5, top plates 6 and end plates 7 are extended in sequence from the opposing side plates 2. The leg plates 5 are overlapped to each other and extended along the side plates 2. They are engaged to each other and temporarily fixed. When the side plates 2 are raised from the bottom plate 1 while the corner pieces 4 are being folded, a goods storing segment 15 is formed through one-finger touch operation from a flat folded state. When the top plates 6 are folded outwardly and the end plates 7 are bent downward, a shock-absorbing segment 16 and an accessory component storing segment 17 are formed.