PURPOSE: To prevent the decomposition of an aqueous solution of a hypochlorite and improve the stability of the salt by adding a specific compound to an aqueous solution of a hypochlorite, thereby sequestering decomposition-inducing heavy metals.

CONSTITUTION: An aqueous solution of a hypochlorite is incorporated with at least one kind of compound selected from (A) a poly-α hydroxyacrylic acid having a molecular weight of 3,000-500,000, its salt or a polylactone or (B) a phosphonic acid compound having hydroxyl group at α-position such as 1- hydroxyethylidene-1,1-diphosphonic acid or its salt in an amount of 10-1,000 pts.wt. based on 1pt. of the heavy metal in the aqueous solution of a hypochlorite. The effect is further improved by the combined use of both components A and B.