To provide a silicon-containing polymer compound which is effective on forming a proton-conductive membrane having a high proton-conductivity, in particular, and small in lowering of proton-conductivity even under the conditions of a high temperature.
The silicon-containing polymer compound contains a repeating unit expressed by formula (1) (in the formula, R1 is a single bond or a methylene group; R2, R3 and R4 are each a 1-20C (halo)alkyl group, a 6-20C aryl group or a silicon-containing group bonding with a silicon atom in the formula, forming a siloxane bond or a silalkylene bond; R5, R6 and R7 are each a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; and X is a hydrogen atom or a counter ion), where the formulae: 0<a/(a+b)<1 and 0≤b/(a+b)<1, are satisfied.
ITO ATSUO
Saori Shigematsu
Katsunari Kobayashi
Takeshi Ishikawa