Abstract: In a method for manufacturing an aqueous solution containing a source of chromium (III) according to the present invention, an aqueous solution containing trivalent chromium is added to an aqueous solution of an inorganic alkali under the condition of a reaction liquid temperature of 0° C. or more and less than 50° C., so that the amount of the trivalent chromium is not locally excessive with respect to the amount of the alkali, to produce chromium hydroxide, and then the chromium hydroxide is dissolved in an aqueous solution of an acid to obtain an aqueous solution containing a source of chromium (III). Preferably, after production of the chromium hydroxide, filtration is performed, and the chromium hydroxide is washed with water until the conductivity of the filtrate is 5 mS/cm or less.

Abstract: Chromium hydroxide of the invention has an average particle size D determined from a scanning electron micrograph of 40 to 200 nm and a degree of agglomeration of 10 and more and less than 70, the degree of agglomeration being defined to be a ratio of a volume average particle size D50 determined with a particle size analyzer to the average particle size D, D50/D. The chromium hydroxide is suitably obtained by adding an aqueous solution containing trivalent chromium to an aqueous solution of an inorganic alkali at a reaction temperature of 0° C. or higher and lower than 50° C. The inorganic alkali is preferably an alkali metal hydroxide.