For sealing an annular space or space (4) between an opening (2), in a wall or similar member (1), and an object (3) extending through the opening (2), at least one sealing element (6) is placed in the annular space (4). Initially, the sealing element (6) is placed in the compressed state between the wall (1) and the object (3) and subsequently is released from the compressed state to an expanded state. For this purpose at first, the sealing element (6) is compressed by a sheath (7) which, after the sealing element (6) is positioned in the annular space (4), is destroyed and makes the expansion of the sealing element (6) possible.