A method for producing a proton conductive electrolyte membrane in which
proton conductivity is sufficiently high, methanol permeability is
sufficiently low and physical strength is sufficient for reducing the
thickness adequately. The production method includes: laminating a
dispersion liquid containing inorganic particles and inflammable organic
particles on an inflammable support, the inflammable organic particles
having an average particle size of 100 to 450 nm; baking the inflammable
support on which the dispersion liquid is laminated; and filling a porous
membrane formed of the inorganic particles obtained by the baking with an
proton conductive organic material.