PURPOSE: To treat only the mouth mold part and to improve plating efficiency, etc., by setting a box for treating the mouth mold which presses and holds on a perforated bottom plate via a gasket and a perforated elastic plate and circulating a treating liquid through the above-mentioned holes.

CONSTITUTION: The above-mentioned device is formed of the box 4 for treating the mouth mold, a treating liquid tank 2, the gasket 5, and a treating liquid circulating means 3. The above-mentioned box 4 is formed of the elastic plate 7 sandwiching the box body bored with the holes 4a on the bottom plate 4B and a steel sheet 7 and a mouth mold push rod 4A disposed on the holes 7a of this plate 7. The above-mentioned gasket 5 is formed of a record disk-shaped gasket 5R, and a pair of double coated tapes 5T stuck to the contact surfaces of the male half mouth mold Km and female half mouth mold Kf assembled by tightening means 6. Further, the above-mentioned circulating means 3 is formed of a pump 3P, a liquid suction pipe 3K, a liquid feed pipe 3S, and a nozzle 3N. The treating liquid (m) is admitted by this nozzle 3N or discharged, by which the liquid is circulated.