In a method for producing a low-molecular-weight fluorine compound by decomposing a fluororesin by bringing a heated microwave absorber into contact with a material containing a fluororesin in a reaction vessel provided with a carrier gas inlet and a decomposition gas outlet, (i) a temperature difference Delta 1(TRTI), obtained by subtracting the carrier gas temperature TI ( C.) from the temperature TR ( C.) of the heated microwave absorber, is set to be more than 500 C. and/or (ii) a temperature difference Delta 2(TRTE), obtained by subtracting the product gas temperature TE ( C.) at the outlet from the temperature TR ( C.), is set to be 300 C. or higher.

Provided is a method for producing a fluoromonomer with an excellent conversion rate of fluoropolymer. The method for producing a fluoromonomer include heating a fluoropolymer in the presence of a metal and/or alloy to obtain a fluoromonomer by thermal decomposition of the fluoropolymer, wherein: a heating temperature during the heating is 300 to 900 C.; and the metal and/or alloy is brought into a molten state during the heating.

Provided is a method for producing a fluoromonomer with an excellent conversion rate of fluoropolymer. The method for producing a fluoromonomer according to the present invention includes heating a fluoropolymer in the presence of an organic sulfur compound to obtain a fluoromonomer by thermal decomposition of the fluoropolymer.