In this study, we have established a novel pretreatment system that improves the juice extraction volume and nutritional value of plant material using underwater shockwaves. The optimum treatment conditions for plant materials were obtained by conducting batch experiments using simple-structured underwater shockwave treatment equipment. From these results, a continuous underwater shockwave processing device was designed. Moreover, we have been demonstrated the applicability and reliability of underwater shockwave pretreatment in improving the yield of functional ingredients and fruit juice from plants. The instantaneous high-pressure dynamic control using underwater shockwaves is applicable to a wide range of extraction processes such as extraction of juices or ingredients from other naturally occurring foods and medicinal plants.