When boards were manufactured with UF resin, the water resis- tance of the board was low because the wax-like substances on the epidermis of rice straw repelled UF resin (Li et al., 2010). On the other hand, the water resistance of the binderless board made from rice straw was relatively high against poor bonding according to wax-like substances on the epidermis of rice straw. Therefore, binderless board was the effective method to utilize the original wax-like substances of rice straw for water resistance of the board. However, it will be necessary to examine the actual effect of wax- like substances on water resistance in further detail in the future.