Fluorine gas is introduced to a raw material liquid containing a reaction inducer and a fluorinated hydrocarbon represented by CpHqClrFs (in the formula, p is an integer of 3 to 18, q is an integer of 0 to 3, r is an integer of 0 to 9, and s is an integer of 5 to 30) and having no carbon-carbon unsaturated bond to give tetrafluoromethane. The reaction inducer is a halogen-containing carbon compound liquid at room temperature and pressure and is reacted with fluorine gas to induce a reaction of forming tetrafluoromethane from the fluorinated hydrocarbon and the fluorine gas. The reaction inducer is contained at a content of more than 0% by mass and not more than 10% by mass when the total content of the fluorinated hydrocarbon and the reaction inducer contained in the raw material liquid is 100% by mass.