To provide a method for producing a vegetable fiber board that has good mold release property for producing the same and is excellent in water resisting properties such as a swelling rate, a water absorption coefficient etc., and in mechanical properties such as peel strength, flexural strength etc., and to provide a binder composition to be used for the same.

The binder composition for vegetable fiber board comprises (A) an organic isocyanate and (B) a maleic acid-based compound, and if circumstances require also one or both of (C) a fatty acid ester compound having a double bond in the molecule and (D) a radical initiator, and the method for producing the vegetable fiber board is to use the binder composition.