PURPOSE: To contrive an accurate retention and protection of an object to be packaged, despite a slight difference in the shape and size between the objects to be packaged, in a cushioning material made of a synthetic resin foam for fitting the object therein for retention.

CONSTITUTION: An engaging part 2 for fitting an object 1 to be packaged therein is provided with a thin plate-like projecting part 3 so deformable as to absorb the difference in the shape and size of the object 1 when it is received in the engaging part. This arrangement requires only a few kinds of the cushioning materials and saves the trouble of providing and controlling many kinds of the cushioning materials.