The invention provides an indium adsorbent that can cause indium to be adsorbed, and a simple and inexpensive indium fractioning method for isolating and recovering high-purity indium from an acid solution whose primary component is hydrochloric acid and that contains indium. A primary component of the indium adsorbent is an anion-exchange resin that has a crosslinked structure produced by the copolymerization of styrene or acrylamide and divinylbenzene, and at least one of a quaternary ammonium group and a tertiary ammonium group, and that is provided with an acid-adsorbing ability. An acid solution whose primary component is hydrochloric acid and that includes indium is brought into contact with the anion-exchange resin to cause indium to be adsorbed to the anion-exchange resin.