Sulfuric acid electrolysis process wherein; a temperature of electrolyte containing sulfuric acid to be supplied to an anode compartment and a cathode compartment is controlled to 30 degree Celsius or more; a flow rate F1 (L/min.) of the electrolyte containing sulfuric acid to be supplied to said anode compartment is controlled to 1.5 times or more (F1/Fa≧1.5) a flow rate Fa (L/min.) of gas formed on an anode side as calculated from Equation (1) shown below and a flow rate F2(L/min.) of said electrolyte containing sulfuric acid to be supplied to said cathode compartment is controlled to 1.5 times or more (F2/Fc≧1.5) a flow rate Fe (L/min.) of gas formed on a cathode side as calculated from Equation (2) shown below. Fa=(I×S×R×T)/(4×Faraday constant)  Equation (1) Fe=(I×S×R×T)/(2×Faraday constant)  Equation (2) I: Electrolytic current (A) S: Time: 60 second (Fixed) R: Gas constant (0.082 1·atm/K/mol) K: Absolute temperature (273.15 degree Celsius+T degree Celsius) T: Electrolysis temperature (degree Celsius) Faraday constant: (C/mol)