The present invention provides an amphiphilic block copolymer, a method for manufacturing the same, and a fuel cell membrane using the same. According to preferred embodiments, the amphiphilic block copolymer may contain poly(arylene sulfone ether ketone) (PSEK) as a hydrophobic component and poly(sulfonated styrene-co-acrylonitrile) (PSSAN) as a hydrophilic component. According to other preferred embodiments, polymer electrolyte membrane manufactured using the amphiphilic block copolymer has certain advantages in that the hydrogen ion conductivity is not reduced even at a high temperature of more than 100° C. but is rather increased and the thermal and chemical dimensional stability is excellent.