A fluorine gas generator for generating fluorine gas by electrolysis of an electrolytic bath comprising a hydrogen fluoride-containing mixed molten salt in which generator the position of the electrolytic bath liquid surface in the electrolytic cell can be safely controlled even during suspension of electrolysis therein is provided. The generator comprises an anode chamber and a cathode chamber separated from each other by a partition wall and is provided with electrolytic bath liquid level controlling means for controlling the electrolytic bath liquid level in at least one of the anode chamber and cathode chamber during suspension of fluorine gas generation.