To provide a sealing method which is small in variance in thickness after the shape is restored, and sufficient in airtightness since a foam having the delayed shape restorability is uniformly restored in shape in the thickness direction thereof.

In sealing a gap between a pipe P and a wall surface or a floor surface making use of the shape restorability of the foam 2, the pipe P is wrapped so that both ends of the foam 2 of the length equal to or slightly larger than the outer circumference of the pipe P are brought into contact with each other, and both end joining parts 3 are fixed to each other.