Provided in the present invention is a redox flow battery including a positive electrode, a negative electrode and a separation membrane, wherein a positive electrode electrolyte composed of an aqueous solution containing vanadium ions is supplied into a positive electrode chamber, and a negative electrode electrolyte composed of an aqueous solution containing vanadium ions is supplied into a negative electrode chamber, to carry out charging and discharging of the battery. In the redox flow battery, zirconium or titanium coated with a noble metal or a compound thereof is used as a positive electrode material, and when the positive electrode material is zirconium coated with a noble metal or a compound thereof, the positive electrode electrolyte and the negative electrode electrolyte contain sulfuric acid; and when the positive electrode material is titanium coated with a noble metal or a compound thereof, the positive electrode electrolyte contains nitric acid.