Abstract: A sealing device for a valve which includes a valve body having a fluid passage and an inner valve for opening or closing said fluid passage, said sealing device comprising a seat packing disposed in a peripheral groove formed in the valve body and partly projecting therefrom into the fluid passage, said seat packing being so constructed that the durability and the fluid shut-off performance are promoted by the combined effect of the fluid pressure in the fluid passage acting against said seat packing and the elastic force of a metallic annular elastic member associated with said seat packing.