To provide a fiber board having high strength, good moisture permeability, and uniform density by obtaining a coconut palm fiber mat with uniform METSUKE (weight).

Coconut palm fibers charged from a hopper 5 are spread planely on a conveyer 4, transported to an upper condenser 6, sucked by the condenser 6, and stuck on the surface of a belt conveyer consisting of a porous substrate, and compressed into a layer with uniform METSUKE (weight). The compressed coconut palm fibers is sent to a lower condenser 7, sucked by the condenser 7, sucked on the surface of a belt conveyer consisting of a porous substrate, and compressed additionally. Subsequently, the laminar compressed fibers are sent to a discharge conveyer 9 through a compression roll 8, intertwined by a needle punching machine 10 locked together, and compacted to obtain a coconut palm fiber mat of uniform METSUKE (weight).