An electrolyte storage unit for redox flow batteries comprising a positive electrode electrolyte storage tank and a negative electrode electrolyte storage tank, wherein each of the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank comprises a water level sensing pipe (14, 24) protruding perpendicularly from one end thereof, wherein the water level sensing pipe has a water level sensor (15, 25) provided therein, and the electrolyte storage unit comprises: a "∩"-shaped electrolyte transfer pipe having a pump provided at a central end thereto to equally adjust a water level of an electrolyte in each of the tanks, wherein one and the other ends of the transfer pipe are disposed to be inserted in a state in which the one and the other ends of the transfer pipe are spaced apart a predetermined distance from the inside sidewall of the water level sensing pipe of each of the tanks, and an electrical control unit configured to measure a water level of the electrolyte in each of the tanks using a water level sensor, thereby automatically operating the pump, wherein, when it is assumed that a cross-sectional area of each of the positive electrode electrolyte storage tank and negative electrode electrolyte storage tank is A and a cross-sectional area of each of the water level sensing pipes of the electrolyte storage tanks is B, the ratio of Ato B is in a range of 2: 1 to 100:1, and wherein the electrolyte is a vanadium-based electrolyte. wherein each of the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank comprises a water level sensing pipe (14, 24) protruding perpendicularly from one end thereof, wherein the water level sensing pipe has a water level sensor (15, 25) provided therein, and the electrolyte storage unit comprises: a "∩"-shaped electrolyte transfer pipe having a pump provided at a central end thereto to equally adjust a water level of an electrolyte in each of the tanks, wherein one and the other ends of the transfer pipe are disposed to be inserted in a state in which the one and the other ends of the transfer pipe are spaced apart a predetermined distance from the inside sidewall of the water level sensing pipe of each of the tanks, and an electrical control unit configured to measure a water level of the electrolyte in each of the tanks using a water level sensor, thereby automatically operating the pump, wherein, when it is assumed that a cross-sectional area of each of the positive electrode electrolyte storage tank and negative electrode electrolyte storage tank is A and a cross-sectional area of each of the water level sensing pipes of the electrolyte storage tanks is B, the ratio of Ato B is in a range of 2: 1 to 100:1, and wherein the electrolyte is a vanadium-based electrolyte. a "∩"-shaped electrolyte transfer pipe having a pump provided at a central end thereto to equally adjust a water level of an electrolyte in each of the tanks, wherein one and the other ends of the transfer pipe are disposed to be inserted in a state in which the one and the other ends of the transfer pipe are spaced apart a predetermined distance from the inside sidewall of the water level sensing pipe of each of the tanks, and an electrical control unit configured to measure a water level of the electrolyte in each of the tanks using a water level sensor, thereby automatically operating the pump, wherein, when it is assumed that a cross-sectional area of each of the positive electrode electrolyte storage tank and negative electrode electrolyte storage tank is A and a cross-sectional area of each of the water level sensing pipes of the electrolyte storage tanks is B, the ratio of Ato B is in a range of 2: 1 to 100:1, and wherein the electrolyte is a vanadium-based electrolyte.