PROBLEM TO BE SOLVED: To provide an adsorbent for hydrothermal decomposition, adsorbing an acid component and/or a heavy metal component generated in hydrothermal reaction treatment and generating a treated subject not containing the acid component and the heavy metal component, and to provide a treatment method using the same.SOLUTION: This adsorbent for hydrothermal decomposition wherein one or both of an oxidizing alkali compound 2 and a heavy metal adsorbent 3 are fixed to a magnetic body 1 is mixed with infectious organic waste and/or chlorine-containing organic waste, and the hydrothermal reaction treatment is performed under conditions of a temperature ≤300°C and a pressure ≤3 MPa.COPYRIGHT: (C)2013,JPO&INPIT【課題】水熱反応処理において発生する酸性成分及び/又は重金属成分を吸着し、酸性成分及び重金属成分を含まない処理物を生成することができる水熱分解用吸着体、及びこれを用いた処理方法を提供する。【解決手段】感染性有機廃棄物及び/又は含塩素有機廃棄物に、磁性体1に酸化性アルカリ化合物2及び重金属吸着剤3のいずれか一方又は双方を固定化した水熱分解用吸着体を混合し、温度300℃以下、圧力3MPa以下の条件で水熱反応処理する。【選択図】図3