PURPOSE: To obtain a zirconium alloy excellent in corrosion resistance and having suitable workability and ductility by adding a specified amt. of Nb as well as specified amounts of Y, Pb, Cu or the like to zirconium.

CONSTITUTION: A zirconium alloy for the constituting member of a nuclear fuel assembly is formed of a compsn. obtd. by adding, by weight, 0.5 to 5% niobium to zirconium and furthermore adding one or ≥ two kinds selected from the group constituted of yttrium, lead, copper, lanthanum, magnesium, calcium, zinc and tin thereto. The zirconium alloy in this invention, i.e., the ternary allay obtd. by adding yttrium, lead or copper to a zirconium-niobium binary alloy is excellent in both mottled corrosion resistance and uniform corrosion resistance compared to those of the conventional zirconium alloy. By using this alloy, the reliability on a nuclear fuel aggregate can be established.