Abstract: A proton exchange polymer membrane whose surface is treated by direct fluorination using a fluorine gas, a membrane-electrode assembly, and a fuel cell comprising the same are provided. The proton exchange polymer membrane of the present invention exhibits improved proton conductivity, high dimensional stability, and decreased methanol permeability through introducing hydrophobic fluorine having high electronegativity to the surface of the polymer membrane. Therefore, the proton exchange polymer membrane with excellent electrochemical properties of the present invention can be preferably utilized as polymer electrolyte membrane for fuel cell, generating electric energy from chemical energy of fuels.