Saccharified solution production method and saccharified solution production apparatus that use cellulosic biomass as starting material

A saccharified solution production apparatus that uses cellulosic biomass as a starting material apparatus as having all the limitations claimed as whole, comprising:

• a saccharifying device for saccharifying hemicellulose or cellulose contained in the cellulosic biomass to C5 saccharides or C6 saccharides by subjecting a slurry of the cellulosic biomass to a hot water treatment in a supercritical state or subcritical state;
• a flush tank for flush evaporating slurry taken from the saccharifying device;
• a heat recovery means that recovers flush vapor and uses it for preheating slurry to be fed to the saccharifying device;
• multiple stages of thickeners for washing successively arranged in series so that the direction of movement of a solid in slurry taken from the flush tank and the direction of movement of an overflow washing water are opposite to each other;
• a thickener for removing a solid residue from overflow washing water taken from the thickeners for washing;
• and
• a concentration device for concentrating a supernatant of the thickener for removing a solid residue from the overflow washing water taken from the thickeners for washing.