A polyfluoroalkane carboxylic acid represented by the following general formula: CnF2n+1(CH2CF2)m(CF2CF2)l−1CF2COOM (M: an alkali metal, a NH4 group or H; n: an integer of 1 to 6; m: an integer of 1 to 4; and l: 1 or 2) can be produced by hydrolysis reaction of polyfluoroalkane carboxylic acid fluoride represented by the following general formula: CnF2n+1(CH2CF2)m(CF2CF2)l−1CF2COF, where its carboxylic acid salt can be formed as an alkali metal salt, or a NH4 salt. The polyfluoroalkane carboxylic acid (or its salt) can act as a surfactant having distinguished monomer emulsifiability and latex stability when used as an emulsifying agent or as a dispersing agent for polymerization reaction of fluorine-containing monomers, or as an effective surfactant capable of enhancing the micelles solubility of fluorine-containing monomers such as vinylidene fluoride, etc., when used as an emulsifying agent or a dispersing agent for homopolymerization or copolymerization reaction of vinylidene fluoride.