A polymer electrolyte composition has excellent practicality and excellent chemical stability as to be able to withstand a strong oxidizing atmosphere during fuel cell operation and is able to achieve excellent proton conductivity under a low-humidified condition and excellent mechanical strength and physical durability, and a polymer electrolyte membrane, a membrane-electrode assembly, and a polymer electrolyte fuel cell produced therefrom. The polymer electrolyte composition includes an ionic group-containing polymer (A), an azole ring-containing compound (B), and a transition metal-containing additive (C), the transition metal being one or more selected from the group consisting of cobalt, nickel, ruthenium, rhodium, palladium, silver, and gold.