PURPOSE: To make a titled adsorbent usable even at elevated temp., by adsorbing and keeping vinylpyridine, vinyl monomer, and a polymerization initiater with granular or crushed activated carbon, and polymerizing them under heating.

CONSTITUTION: 0.5W20pts.wt. vinyl monomer and a proper quantity of polymerization initiator are dissolved in 100pts.wt. vinylpyridine to obtain a solution. The solution is added dropwise to the granular or crushed activated carbon and both of them are mixed to keep the mixture in absorbed state. And the total amount of vinylpyridine, vinyl monomer, and polymerization initiator to be added to the activated carbon is ≤40wt%. This metallic ion adsorbent can be used stably without causing any deterioration and decomposition at elevated temp.