The 12CaO 7Al2O3 chemical compound which includes the hydrogen anion (H -) of density of 1 1018 cm 3 or more and/or 12SrO 7Al2O3 chemical compound and the anti- oxidizer which designates those mixed crystals as the active ingredient.1×1018cm-3以上の濃度の水素陰イオン(H-)を含む12CaO・7Al2O3化合物及び/又は12SrO・7Al2O3化合物およびそれらの混晶を有効成分とする抗酸化剤。