We synthesized a novel adsorbent to recover inorganic arsenic(III) from groundwater, and we investigated its adsorptivity. The adsorbent, which was made by soaking powder made from crushed fisheries waste (scallop shells) in an iron sulfate solution without heat or pressure, adsorbed 0.2mg of arsenic(III) per gram of adsorbent. This high adsorptivity and the inexpensive, simple, and environmentally benign synthesis method indicate that this easy-to-handle adsorbent may be useful for preparing safe drinking water from groundwater contaminated with toxic arsenic(III).