PURPOSE: To arbitrarily regulate coating width without altering the center position of the coating width by providing the deckle extending to the leading end of a slit in a liquidtight state and the deckle guide and seal piece arranged to the slit in a non-liquidtight state to the slit.

CONSTITUTION: An inner deckle shaft 5 brought to a liquidtight state in the vicinity of the leading end thereof and movable in a liquidtight state is provided in a manifold 3 and the deckles 7 brought to a liquidtight state with respect to a slit 4 and connected to the liquidtight state part 6 of the inner deckle shaft 5 to extend up to the leading end of the slit 4 from the manifold 3 are arranged to the inner deckle shaft 5. The deckle guides fixing the deckles 7 are arranged to the slit 4 in a non-liquidtight state and the seal pieces 20 extending up to the leading end of the slit 4 are provided to the slit 4 in a non-liquidtight state behind the deckles 7.