NOVELTY - The membrane comprises a mixed layer formed in a side of a 3D network structure supporter that is arranged with an ion migration domain. The 3D network structure supporter is made of an ion-conductive material. Thickness of the mixed layer is 30 micrometers or less. A pure water layer is laminated in an upper side of the mixed layer. Thickness of the pure water layer is 6 micrometers or less. Thickness difference between the mixed layer and the pure water layer is 50% or less. The ion-conductive material is semi-crystalline polymer or hydrocarbon material.    USE - Polymer electrolyte membrane for use in a membrane electrode assembly of a fuel cell e.g. alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), fusing carbonate thermal electric cell, solid oxide fuel cell (SOFC), polymer electrolyte fuel cell (PEMFC) and direct methanol fuel cell (DMFC) (all claimed), that is utilized for an internal combustion engine vehicle and a portable power source for a portable apparatus in a home and an electricity industry.    ADVANTAGE - The high temperature humidification and drying operation about the membrane are effectively performed by repeating contraction and expansion of the membrane according to task operation state of the membrane so as to improve durability and operating performance of a fuel cell.    DETAILED DESCRIPTION - The membrane comprises cationic exchange agent such as sulfonic acid group, carboxylic acid group or phosphate group material. The ion-conductive material is a sulfonation benzimidazole group polymer, a sulfonation polyimide system polymer, a sulfonation polyetherimide group polymer, a sulfonation polyphenylenesulfide group polymer, a sulfonated polysulfone polymer, a sulfonal polyether sulfone polymer, a sulfonated polyetherketon polymer, a sulfonation polyether-ether ketone polymer, a sulfonation polyphenyl quinoxalin group polymer or sulfonation fluoride group material.    DESCRIPTION OF DRAWING(S) - The drawing shows a graphical view illustrating relationship between RH cycle result and hydrogen crossover current density of a polymer electrolyte membrane.'(Drawing includes non-English language text)'