To provide a flame retardant foaming buffer sheet having protruded closed cells without using a halogen fire retardant.

In a foaming buffer sheet 1 having protruded closed cells in which an embossed film 22 in which a lot of embossments 21 are formed and a plane base film 24 are laminated, the embossed film 22 and the base film 24 are a polyethylene composition containing 100 pts.wt. of an ethylene-α-olefin copolymer and 20-150 pts.wt. of a metal hydrate.