An inner deckle for a die includes a shaft-shaped deckle main body and a sheet- or film-shaped deckle auxiliary portion extending from the deckle main body. The inner deckle is arranged at each end of a die. The die includes a die piece and is formed with a manifold and a slit. The deckle main body includes a seal reinforcing portion. A liquid material is supplied into the manifold. The seal reinforcing portion includes at least one sealing member having two or more films. The films slide and are simultaneously elastically deformed against an inner wall of the manifold when a position of the inner deckle is moved with respect to the die. The films cooperate with each other and are closely attached to the inner wall by an elastic restoring force when the position of the inner deckle is fixed with respect to the die.