Accordingly, rice straw boards bonded with synthetic resin have many compatibility issues between the raw materials and resins. On the other hand, binderless board, a board that contains no resin, is potentially an effective solution to overcome these issues while also avoiding the formaldehyde emission associated with UF resin. The absence of adhesive meets both environmental and economic requirements. Binderless boards have been successfully manufactured from Miscanthus sinensis (Velasquez et al., 2003) and wheat straw (Halvarsson et al., 2009), which, like rice, belong to the Poaceous family. There has been no information about properties of binderless boards made from rice straw until now. Therefore, the purpose of this study was to manufacture binderless boards from rice straw and to discuss the morphological effect of particles from rice straw on the properties of the boards. For the morphological effect of particles, we examined the influence of particle size and the morphological part of rice straw.