PURPOSE: To enable lightly opening a toilet cover and a toilet seat and to prevent the rapid drop of the toilet cover and the toilet seat at the time of closing by providing the cover and the seat with a one-way damper function having a valve.

CONSTITUTION: At the time of opening a toilet cover 5, a mounting part 5a of the toilet cover 5 is fitted. A blade part 7b of a rotation drum 7 is rotated counterclockwise in cylinder parts 25a and 25b and a bulb valve 23 is oscillated in a long groove 19 and release the close for a long hole 15. Thus, viscous liquid 26 moves from the cylinder part 25a to the 25b and from the cylinder part 25b to the 25a and the toilet cover 5 is opened lightly. On the other hand, when the toilet cover 5 is closed, the bulb valve 23 is oscillated at the side of the 2nd bulb chip 22 to clog the long hole 15 and the flow of the viscous liquid 26 flows only through a circular groove 18a. Thus, the damper function is operated and the toilet cover 5 does not drop rapidly and it is closed quietly.