PURPOSE: To give wide and durable seal action to a conduit having a different material or strength, regardless of intensity of pressure of the conduit, and even in the case of applying high load to the connected part.

CONSTITUTION: On both end parts of an annular seal material 8 arranged in a housing 4 covering the circumference of a pipe, an annular bead 12 projecting toward the outer wall of the conduit is formed, and the annular bead 12 is provided with an annular gap 13 dividing it into a first radial bead part 14 positioned on the inside of the seal material 8 and a second radial bead part 18 positioned on the outside of the seal material 8. By slantingly extending the gap 13 from a seal face 15 to the annular bead 12, the second radial bead part 18 adjacent to the gap 13 is formed with a sealing lip 21 of acute angle.