To provide a proton conductive composite electrolyte membrane in which both superior proton conductivity and low fuel permeability are made compatible, and capable of retaining high proton conductivity even under low humidity in a comparatively high temperature area.

The proton conductive composite electrolyte membrane contains an inorganic material having proton conductivity, an organic material having proton conductivity and ionic liquid. A content of the inorganic material is 10 to 60 wt.% to the total weight of the electrolyte membrane, and a content of the ionic liquid is 1 to 100 pts.wt to 100 pts.wt of the inorganic material.