NOVELTY - Tetravalent vanadium ion solution in which total content of aluminum, calcium, sodium, potassium, iron, silicon and/or chromium is less than 0.4 %mass and dissolved oxygen content is 0.1 ppm or less, is prepared. The obtained tetravalent vanadium ion solution is oxidized and electrolyzed under deaerated atmosphere to obtain pentavalent vanadium ion solution, and simultaneously divalent vanadium ion solution is obtained by reducing and electrolyzing tetravalent vanadium ion solution in deaerated atmosphere. Thus, vanadium electrolyte solution is manufactured.    USE - Manufacture of vanadium electrolyte solution used for redox non-flow battery and redox flow battery.    ADVANTAGE - The method efficiently provides vanadium electrolyte solution with reduced generation of sludge, by oxidation/reduction reaction.    DETAILED DESCRIPTION - Tetravalent vanadium ion solution in which total content of aluminum, calcium, sodium, potassium, iron, silicon and/or chromium is less than 0.4 %mass and dissolved oxygen content is 0.1 ppm or less, is prepared. The obtained tetravalent vanadium is oxidized and electrolyzed under deaerated atmosphere to obtain pentavalent vanadium ion solution, and simultaneously divalent vanadium ion solution is obtained by reducing and electrolyzing tetravalent vanadium ion solution in deaerated atmosphere. Thus, vanadium electrolyte solution is manufactured. An INDEPENDENT CLAIM is included for manufacturing apparatus of vanadium electrolyte solution, which has primary electrolysis cell for performing oxidation and reduction of vanadium ion with same electric charge, and secondary electrolysis cell for performing oxidation of vanadium ion with the same electric charge as the oxidation in primary electrolysis cell, primary circulation tank for circulating the vanadium ion solution which is provided to an oxidation reaction by the oxidation electrolysis chamber, secondary circulation tank for circulating vanadium ion solution which is provided to a reductive reaction by reduction electrolysis chamber, other circulation tank for circulating electrolyte solution other than the vanadium ion solution which is provided to an oxidation reaction by the oxidation electrolysis chamber with which secondary electrolysis cell is equipped, inert gas supply apparatus for supplying inert gas in primary circulation tank and secondary circulation tank.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart electrolyte solution. (Drawing includes non-English language text)