To obtain a soft Zr alloy for a nuclear reactor material having soft mechanical properties equal to those of pure Zr while its restraint on rapid oxidation is maintained and excellent in hydrogen absorbing characteristics and stress corrosion cracking resistance in a high temp.-high pressure water vapor atmosphere by adding a specified amt. of Fe to Zr and furthermore regulating the contents of O and other inevitable impurities to specified ones.

In Zr, as trace additives, by weight, 0.1 to 0.6%, preferably, 0.1 to 0.4% Fe is contained, and the content of O is regulated to ≤1200ppm and that of other inevitable impurities is regulated to ≤2000ppm. Furthermore, for the minute regulation of its corrosion resistance, alloy elements such as Ni can be added thereto, and at this time, as for their amounts to the added, e.g. the content of Ni is preferably regulated to about 0.1 to 0.4% which is the range not deteriorating its hydrogen absorbing characteristics. In this way, while the various characteristics of the soft Zr alloy are maintained, its hydrogen absorbing characteristics and stress corrosion cracking resistance are improved.