The method of manufacturing nickel sulfate

PROBLEM TO BE SOLVED: To provide a production method of nickel sulfate, allowing for prevention of the occurrence of sulfur, thereby allowing for suppression of sulfur contamination in an obtained nickel sulfate crystal.SOLUTION: The production method of nickel sulfate is provided in which nickel sulfate is crystallized from a solution containing nickel sulfate (nickel-sulfate-containing solution) to obtain a nickel sulfate crystal. The production method has an oxidation step of oxidizing the nickel-sulfate-containing solution by adding ozone to the nickel-sulfate-containing solution before crystallization in such a way that an oxidation reduction potential measured by using a reference electrode of a silver-silver chloride electrode is 1,000 mV or higher while keeping the nickel-sulfate-containing solution at a pH of 1.0-3.0.SELECTED DRAWING: Figure 1