Disclosed are: a reinforced composite membrane-type polymer electrolyte membrane which can prevent the loss of an ion conductor even when the ion conductor is chemically deteriorated due to long-term use, and thus has remarkably enhanced mechanical and chemical durability; a method for manufacturing same; and an electrochemical device comprising same. The polymer electrolyte membrane of the present invention comprises: a non-crosslinked ion conductor; and a porous support having a plurality of pores filled with the ion conductor, wherein the porous support comprises a polymer having at least one crosslinking functional group, and the crosslinking functional group is a functional group which, when the ion conductor is deteriorated, can cause crosslinking of the ion conductor by binding to the deteriorated ion conductor.