NOVELTY - A solid polymer electrolyte contains aromatic hydrocarbon type polymer compound which consists of specific repeating unit, and sulfonic acid as substituent. The oxidation degree (x) of sulfur atom in the repeating unit is 1.2-2.    USE - As solid polymer electrolyte film, catalyst electrode layer, film/electrode laminate, fuel cell (claimed), film for water electrolysis, hydrohalic acid electrolysis, brine electrolysis, diffusion dialysis and battery diaphragm, oxygen enricher, humidity sensor, gas sensor. The polymer electrolyte fuel cell is used for space or military, and the fluorine type electrolyte film is used as polymer electrolyte fuel cell as low pollution power source for motor vehicles.    ADVANTAGE - The polymer electrolyte is inexpensive and has excellent durability, moist- and heat-resistance, and oxidation resistance. The film, catalyst electrode layer and fuel cell obtained using the polymer electrolyte has favorable property.    DETAILED DESCRIPTION - A solid polymer electrolyte contains aromatic hydrocarbon type polymer compound which consists of repeating unit of formula (1):-(-Ar-SOx-)-, and sulfonic acid of formula (2):-R1-SO3H as substituent. The oxidation degree (x) of sulfur atom in the repeating unit is 1.2-2.    Ar=bivalent aromatic and its derivatives;    x=oxidation degree of sulfur atom;and    R1=alkyl group and their derivatives, alkyl group having at least 1 during atom as substituent and their derivatives, aromatic group and their derivatives.    INDEPENDENT CLAIMS are included for the following:    (i) manufacture of solid polymer electrolyte which involves introducing sulfonic acid (2) and sulfonamide sulfonic acid of formula (3) -O2SHN-R2-SO3H: to polyarylene sulfide type polymer as substituent and oxidizing sulfide to sulfone.R2=R1;    (ii) solid polymer electrolyte film which consists of solid polymer electrolyte;    (iii) catalyst electrode layer which is used as catalyst electrode which made a surface of electroconductive material consisting of carbon material support the microparticles of crystal metal from the solid polymer electrolyte;    (iv) film/electrode laminate which consists of the catalyst electrode layer of the solid polymer electrolyte film; and    (v) fuel cell which used the film/electrode laminate.