Disclosed herein is a polyarylene-based polymer, a preparation method for the same, and a polymer electrolyte membrane for fuel cell using the polymer. The polyarylene-based polymer, which is designed to have long side chains of a hydrophilic moiety and dense sulfonic acid groups, may improve the formation of ion channels when fabricating a polymer membrane and also ensures good chemical stability of the hydrophilic moiety and good dimensional stability against water. Further, the preparation method of the present invention simplifies production of the polymer, and polymer electrolyte membranes using the polymer exhibits improved properties as a polymer electrolyte membrane for a fuel cell, such as high proton conductivity, even under an atmosphere of low water uptake, and good dimensional stability against a long-term exposure to water.