The purpose of this study is to develop a green composite with a high strength and stiffness, using long bamboo fibers, in order to apply biomass resources for practical use. Two kinds of biodegradable resins were used as a matrix of the composite, and hot-pressed with the reinforcement. In addition, bamboo fibers were dyed to create a good interfacial bonding between the fiber and matrix, and compared with untreated fiber reinforcement. In this study, furthermore, the effect of water content included in the composite on the mechanical properties of the composite was explored. The results show that the composites indicate a relatively large tensile strength, comparable to ramie fiber-or Manila hemp fiber-reinforced green composites. On the other hand, dyeing for the fibers and water content in the composite did not significantly affect their mechanical properties.