To make an inner packing pass smoothly into a feed water hole and pressure-fit the inner packing positively to the internal wall surface of a toilet bowl so as to heighten sealing performance.

An inner packing 7 of plate shape is fitted to the outer periphery of a hollow cylindrical body 3 inserted into a feed water hole 2 of a toilet bowl 1, and a spring washer 8 is fitted between the inner packing 7 and a collar part 4 of the hollow cylindrical body 3. This spring washer 8 consists of a washer part smaller in diameter than the feed water hole 2, and a plurality of resilient blade plate parts 10 protrusively provided on the outer peripheral side of the washer part radially and inclining in an opposite direction of the insert direction of the hollow cylindrical body 3 and formed in such a way that the outer diameter is larger than the inner diameter of the feed water hole 2. The inner packing 7 and the spring washer 8 are inserted in the toilet bowl 1 from the feed water hole 2, and the inner packing 7 is opposed to the internal wall surface of the toilet bowl 1. A nut 14 is fastened from the outside to fix the hollow cylindrical body 3 to the toilet bowl 1, and the inner packing 7 is pressed to the internal wall surface of the toilet bowl 1 by the blade plate parts 10 of the spring washer 8.