A polymer electrolyte membrane includes a cross-linking reaction product between a hydrophilic polymer and a cross-linking agent represented by Formula 1 below wherein R1 is substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C6-C20 aryl group, or substituted or unsubstituted C2-C20 heteroaryl group; and n is an integer in the range of 1 to 5. The polymer electrolyte membrane may be prepared by preparing a composition for forming a polymer electrolyte membrane including the hydrophilic polymer, the cross-linking agent represented by Formula 1 and a solvent, applying the composition for forming a polymer electrolyte membrane to a supporting substrate; and heat treating the composition for forming the polymer electrolyte membrane to form the polymer electrolyte membrane. A fuel cell or other device includes the polymer electrolyte membrane. The polymer electrolyte membrane has low solubility to a strong acid and excellent ionic conductivity. Also, the polymer electrolyte membrane is suitable for high temperatures and has excellent durability obtained by reinforcing the mechanical strength of the electrolyte membrane. By employing such a polymer electrolyte membrane, a fuel cell having excellent efficiency, etc. can be prepared.