NOVELTY - A fluoro polymer contains acid or its salt group and difluoro methane group in polymer chain terminal. The acid group is sulfonic acid group (1) or phosphoric acid group (2).    USE - For electrolyte film, active substance fixed component, film-electrode conjugant for solid polymer electrolyte type fuel cell (all claimed).    ADVANTAGE - The fluoro polymer having excellent stability and improved durability is provided.    DETAILED DESCRIPTION - A fluoro polymer contains acid or its salt group and difluoro methane group in polymer chain terminal. The acid group is sulfonic acid group (1) of formula: -SO2NR1R2, -SO3NR3R4R5R6 or -SO3M11/_L, or phosphoric acid group (2) of formula: -PO3(NR7R8R9R10)2 and/or -PO3M22/_L.    R1=H or M61/_L;    R2=H, M71/_L, alkyl or sulfonyl-containing group;    R3-R10=H or 1-4C alkyl;and    M1,M2,M6,M7=metal of valence L chosen from group 1, 2, 4, 8, 11, 12 or 13 of periodic table.    INDEPENDENT CLAIMS are included for the following: (i) fluoro polymer manufacturing method, which involves heat processing fluoro polymer precursor having acid/its salt group and carboxyl group of formula: -CF2COOX at the polymer terminal and converting the carboxyl group to difluoro methane group. The polymer precursor is obtained by polymerizing perhalo vinyl ether derivative of formula: CF2=CF-O-(CF2-CFY1-O)n-(CFY2)m-SO2Z.    X=H, NR11R12R13R14 or M4;    Y1=fluorine, chlorine or perfluoro alkyl group;    n=0-3;    Y2=fluorine or chlorine;    m=1-5;    Z=fluorine, chlorine, bromine, iodine, -OM51/_L or -ONR15R16R17R18;    M5=metal of valence L;and    R15-R18=H or 1-4C alkyl.    The -SO2Z group is converted into acid or its salt group after polymerization. The polymer precursor is heat-processed at 120-400degreesC; (ii) electrolyte film which consists of the fluoro polymer; (iii) active substance fixed component which consists of the fluoro polymer and active substance; (iv) film-electrode conjugant which consists of the active substance fixed component; and (v) solid polymer electrolyte type fuel cell which has the film-electrode conjugant or electrolyte film.