PURPOSE: To obtain a Zn alloy having excellent corrosion resistance in water and steam at high temp. and high pressure by incorporating one or more kinds of specific amounts of Nb, V, Mo, Ta and W into a Zn-Sn-Fe-Cn-Ni alloy or a Zn-Sn-Fe-Cr alloy.

CONSTITUTION: As the material such as a fuel covering tube and a core structural material of a boiling-water reactor and a pressurized-water reactor used in water and steam at high temp. and high pressure, a Zr alloy having the comspn. contg., by weight, 0.5W1.7% Sn, 0.05W0.5% Fe and 0.05W0.3% Cr, furthermore contg. total 0.005W0.5% of one or more kinds among Nb, MO, W, V and Ta and the balance Zr, or a Zr alloy having the above compsn. and the which ≤0.1% Ni is furthermore added and incorporated is used. The Zr alloy having excellent corrosion resistance in an environment where it is brought into contact with high temp. and high pressure-water and steam can be obtd.