A method for producing fluorine gas including electrolyzing an electrolyte in an electrolytic cell, measuring an intensity of sound generated near an anode in an inside of the electrolytic cell as the electrolyte is electrolyzed in the electrolyzing, and sending a fluid generated in the inside of the electrolytic cell in the electrolyzing the electrolyte, from the inside to the outside of the electrolytic cell through a flow path. The flow path is switched in accordance with the intensity of sound measured, such that the fluid is sent to a first flow path when the intensity of sound measured in the measuring an intensity of sound is not more than a predetermined reference value, or the fluid is sent to a second flow path when the intensity of sound measured in the measuring an intensity of sound is more than the predetermined reference value.