PURPOSE: To carry out regeneration treatment of a large quantity of contaminated gel favorably in industrial use, by treating the contaminated gel with aqueous solution of a specific salt of high temperature and high concentration.

CONSTITUTION: Regeneration treatment is carried out by treating contaminated gel lowered the separation capacity by an aqueous solution of metallic salt or ammonium salt of 30wt%W saturated concentration thiocyanic acid, nitric acid or hydrogen iodide at 50W120°C. The metallic salt or ammonium salt of the thiocyanic acid, especially alkali metal salt or ammonium salt of the thiocyanic acid, is preferable for adopting salt as regards to the regeneration capacity of the contaminated gel and the aqueous solution is used preferably for industrial use as a water solution. Further, 50W120°C treating temperature, especially a preferable condition within the range of 90W120°C, is necessary to adopt. The gel carried out such a regeneration treatment is returned to an original operation condition after washing by a solvent next and said gel is reused.