To improve a buffer envelope, which is composed of an inner buffer layer of a plastic foam sheet and an outer craft paper envelope, to provide a product, which has no interposed sealed parts of the foam sheet on the bottom side and both sides and those sides are formed by gluing papers together, has a superior appearance and sufficient strength, and is easy to collect separately for recycling.

A plastic foam sheet is doubled to form a fold as a bottom side (11), and is heat sealed and fusion cut at a given distance to form both sides (12) to form a buffer bag as the buffer layer of plastic foam sheet. A craft paper bag is made to have length and width which exceed in size slightly the same of the buffer bag (1), and the front and back faces of the buffer bag is glued together at the exceeding portion via an adhesive (7) to form the bottom side (21) and both sides (22), which form a paper bag (2). The buffer bag and the paper bag are bonded together with an adhesive (8) at a part near the mouth of the buffer bag.