Abstract: Provided is a high-concentration vanadium electrolytic solution containing a high concentration of vanadium ions, which could not conventionally be prepared, and which can be used in a circulation-type redox flow battery or a non-circulation-type redox non-flow battery and in which sludge is unlikely to be generated, and a method and a device for producing the same. To solve the above-discussed problems, the vanadium electrolytic solution which is a sulfuric acid solution, includes vanadium ions in the range of from over 1.7 mol/L to 3.5 mol/L.