Method for treating cellulose-containing biomass

A treatment method for biomass, which is a pretreatment method comprising continuously performing hydrothermal treatment through use of a screw extruder to produce a biomass composition for saccharification from cellulose-containing biomass serving as a raw material,

• the treatment method sequentially comprising:
• pulverizing, in a pulverization section of the screw extruder, the cellulose-containing biomass
• serving as a raw material so as to have a maximum grain size of 1,000 μm or less and
• adjusting a water content ratio thereof to from 20% to 80%;
• performing, in a heating section of the screw extruder, hydrothermal treatment at a temperature of from 150° C. to 250° C. for 0.1 minute to 10 minutes while performing kneading pulverization having a grinding effect;
• and
• cooling, in a cooling section of the screw extruder downstream of the heating section, a treated product to 100° C. or less to recover the treated product of the cellulose-containing biomass having an average grain size of 100 μm or less.