A medical adsorbent which produces minimal side-effects such as constipation, has excellent adsorption for ionic organic compounds such as causative substances of uremia, exhibits adequate adsorption performance at low doses and avoids adsorption of high-molecular compounds necessary for the body, such as enzymes and polysaccharides. The medical adsorbent comprises activated carbon obtained by carbonizing a spherical phenol resin in a nitrogen atmosphere at a temperature of 400-1000.degree. C., activating the carbonized spherical phenol resin at a temperature of 800-1000.degree. C., washing it with dilute hydrochloric acid, heat treating it at a temperature of 150-1000.degree. C. in a mixed gas comprising oxygen and nitrogen and then sorting it; the activated carbon has an area to weight ratio of 500-2000 m.sup.2/g, a pore volume of 0.2-1.0 mL/g and a packing density of 0.5-0.75 g/mL.