A board capable of capturing and decomposing both formaldehyde and acetaldehyde comprises a wood fiber board comprising a plant fiber of 30 wt % or more, and an aldehyde capturing agent comprising at least carbodihydrazide which is impregnated and solidified inside the side of the fiber board. In addition to the wood fiber board, a fiber board made of a mixture material of a resin fiber and a plant fiber combined. A carbodihydrazide is sprayed onto the fiber board in the form of water solution and optionally comprises a surfactant.