▎ 摘　　要

NOVELTY - Composite electrolyte membrane comprises (a) ion conductive polymer, (b) polyamic acid or its salt, diamine compound and acid dianhydride, and first additive containing polyamic acid or its salt, diamine compound and/or acid dianhydride, and second additive containing metals, metal ions or its salts, metal oxides, metal alloys, and/or graphene oxide. USE - The composite electrolyte membrane is useful in fuel cell and polymer electrolyte fuel cell for device including transportation means, energy storage unit, household fuel cell, and portable fuel cell (all claimed). ADVANTAGE - The composite electrolyte membrane has excellent durability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: producing composite electrolyte membrane; electrode comprising (a1) electrode catalyst, (b1) polyamic acid or its salt, diamine compound and acid dianhydride, and first additive, and (c1) second additive; preparation of electrode; membrane-electrode assembly; and polymer electrolyte fuel cell.