NOVELTY - Biomass is pre-processed by mixing lignocellulosic biomass and aqueous ammonia as substrate, obtaining substrate mixture, heating substrate mixture to predetermined temperature and maintaining predetermined temperature over predetermined period to dissociate lignin from substrate or make substrate swell and obtain ammonia-containing saccharification pre-processed material, diffusing and separating ammonia from ammonia-containing saccharification pre-processed material, cooling and condensing diffused ammonia, dissolving in water, and collecting aqueous ammonia.    USE - Pre-processing method of biomass (claimed).    ADVANTAGE - High concentration of ammonia can be efficiently cooled at low cost.    DETAILED DESCRIPTION - Biomass is pre-processed by mixing lignocellulosic biomass and aqueous ammonia as substrate, obtaining substrate mixture, heating substrate mixture to predetermined temperature and maintaining predetermined temperature over predetermined period to dissociate lignin from substrate or make substrate swell and obtain ammonia-containing saccharification pre-processed material, diffusing and separating ammonia from ammonia-containing saccharification pre-processed material, cooling and condensing diffused ammonia, dissolving in water, collecting aqueous ammonia, and obtaining saccharification pre-processed material. Ammonia diffused from ammonia-containing saccharification pre-processed material is cooled with 2nd thermal medium which is cooled at low temperature until amount of ammonia decreases to predetermined amount. The 2nd thermal medium is supplied to heat pump (19) for heating 1st thermal medium which heats substrate mixture. Circulation path makes part which cools heat pump and ammonia circulate through 2nd thermal medium. The 2nd thermal medium is stored. Pre-processing method of biomass is batch type.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of an apparatus which performs pre-processing method of biomass.    Preprocessor (1)    Reaction container (2)    Ammonia condenser (3)    Ammonia absorption tower (4)    Heat pump (19)