An adsorbent for oral administration, characterized by comprising a spherical activated carbon prepared from a thermosetting resin as a carbon source, wherein a diameter is 0.01 to 1 mm, and a specific surface area determined by Langmuir's adsorption equation is 1000 m2/g or more; and an adsorbent for oral administration, characterized by comprising a surface-modified spherical activated carbon prepared from a thermosetting resin as a carbon source, wherein a diameter is 0.01 to 1 mm, a specific surface area determined by Langmuir's adsorption equation is 1000 m2/g or more, a total amount of acidic groups is 0.40 to 1.00 meq/g, and a total amount of basic groups is 0.40 to 1.10 meq/g. The adsorbents for oral administration exhibit a useful selective adsorbability, that is, a less adsorbability of useful substances in a body, and a greater adsorbability of toxic substances.