PURPOSE: To simplify the continuity of PC steel inserting sheaths of filling concrete continuous with existing concrete members and provide water stop performance.

CONSTITUTION: A spiral sheath 2A in an existing concrete member 1A is connected to the spiral sheath 2B of a filling concrete part 1B by a sheath joint 10. The sheath joint 10 is formed of a joint body 11 and elastic packing material 12. The joint body 11 is provided with a spiral cylinder part 11a, screw-fitted to the periphery of one sheath 2B, at one end thereof; a plain cylinder part 11b, inserted into the other sheath 2A, at the other end thereof; and a step part 11c between both cylinder parts 11a, 11b. The elastic packing material 12 is fitted to the periphery of the plain cylinder part 11b with adhesive 15 stuck to one face.