An endotoxin adsorbent comprising a crystalline cellulose having a nitrogen atom-containing cationic group can sufficiently remove endotoxin from a material containing endotoxin to be removed and containing a substance having a cationic group and can efficiently remove endotoxin also from a highly viscous material. The nitrogen atom-containing cationic group may be typically a functional group derived from a polyvalent amine and/or a quaternary ammonium salt. The crystalline cellulose having a nitrogen atom-containing cationic group may comprise the nitrogen atom-containing cationic group at a content of 0.05 to 3 meq/dry.g in terms of anion exchange capacity.
