We have developed a novel rice straw collection system that incorporates compression-grinding method combined with lime treatment for use on rice farms. In this study, we determined the improvement in sugar yield by enzymatic saccharification and in resistance to biological decomposition by processing wet rice straw by using the proposed treatment method. Our proposed pretreatment method for rice straw successfully improved the sugar yield and resistance to biological decomposition. Pretreatment of rice straw by compression grinding combined with lime treatment can be conducted on the farm itself, immediately after harvest. Thus, incorporation of this method for the rice straw collection in bioethanol production may allow for the skipping of conventional drying step on farms and other pretreatment process performed for enzymatic saccharification in plants and for the effective utilization of previously abandoned difficult-to-dry wet biomass as feedstock in bioethanol production. Skipping of these steps would reduce the cost of ethanol production.