NOVELTY - A hydrothermal decomposition apparatus has a biomass supply apparatus (31), decomposition apparatus main portion (42A) and extraction apparatus (51). The supply apparatus carries out supply of biomass material (11) placed at normal pressure to elevated pressure. Hot water (15) is supplied to main portion. The biomass is hydrothermally decomposed by contact with hot water. Lignin component and hemicellulose component are transferred to hot water and separated. The extraction apparatus ejects biomass solid (17) from apparatus main portion.    USE - Hydrothermal decomposition apparatus is used in system for manufacturing organic raw material, such as petroleum substitute product and amino acid (claimed).    ADVANTAGE - The hydrothermal decomposition apparatus efficiently enables recovery of hexose and pentose component.    DETAILED DESCRIPTION - A hydrothermal decomposition apparatus has a biomass supply apparatus (31), decomposition apparatus main portion (42A) and biomass extraction apparatus (51). The supply apparatus carries out supply of biomass material (11) placed at normal pressure to elevated pressure. The apparatus main portion supplied with biomass is moved in compressed state through interior of main portion from end sides. Pressurized hot water (15) is supplied to main portion from other end side, which different from supply side of biomass. The biomass is hydrothermally decomposed by countercurrent contact with hot water. The lignin component and hemicellulose component are transferred to hot water and separated from biomass. The extraction apparatus ejects biomass solid (17) from apparatus main portion at side, in which hot water is supplied, from elevated pressure to normal pressure atmosphere. An INDEPENDENT CLAIM is included for manufacturing system of organic raw material. The system has preprocessor for pre-processing biomass feedstock hydrothermal decomposition apparatus, enzymatic decomposition apparatus and fermentation apparatus. The enzymatic decomposition apparatus carries out treatment of cellulose contained in biomass solid using enzyme, and cellulose is decomposed into a sugar solution containing hexose. The fermentation apparatus carries out fermentation processing of sugar solution to produce alcohol, petroleum substitute product or amino acid.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of hydrothermal decomposition apparatus. (Drawing includes non-English language text)    Biomass material (11)    Hot water (15)    Biomass solid (17)    Biomass supply apparatus (31)    Main portion (42A)    Biomass extraction apparatus (51)