The objective of the present invention is to obtain an adsorbent having high adsorption capacity and high strength comprising porous cellulose beads obtained without using an auxiliary material which is highly toxic and corrosive and without a cumbersome and industrially adverse step. The present invention is characterized by immobilizing a ligand onto porous cellulose beads obtained by mixing a cold alkaline aqueous solution and cellulose powder as a raw material to prepare a cellulose dispersion and bringing the cellulose dispersion into contact with a coagulating solvent.