PURPOSE: To maintain the sealing effect of a seal valve for a long time by executing the service life of a sheet rubber in the seal valve for raw material charging equipment in a blast furnace.

CONSTITUTION: The seal valve is made into the double structure of an inner ring and an outer ring with a seat bases 15a1, 15a2 in the valve body 14a of the seat valve and the sheet rubber 17a facing to the seat bases, and between the seat base 15a2 of the outer ring and the seat rubber 17a, gap A is arranged. When the seat rubber 17a is abraded, the seat base of the outer ring is brought into close contact with the seat rubber and the sealing effect of the seal valve is maintained.