The adsorption of α-chymotrypsin onto plant biomass charcoal (PBC), which was prepared from plant biomass wastes such as bagasse and dumped adzuki beans by pyrolysis, has been examined. The PBC was characterized by SEM, specific surface area, and pore size distribution. The adsorption isotherms were successfully correlated by the Freundlich equation. The amount of α-chymotrypsin adsorbed on PBC was dramatically dependent upon the solution pH and temperature. Maximum adsorptions of α-chymotrypsin on adzuki bean charcoal and bagasse charcoal were observed at weak acidic and near neutral pH, respectively. The amount of α-chymotrypsin adsorbed on PBC decreased with an increase in the concentration of salts. Plots of the amount of α-chymotrypsin adsorbed on PBC versus temperature exhibited an optimum temperature.