To provide a zirconium alloy used for structural parts as well as cladding pipe for fuel rod for a nuclear reactor and improved in hydrogen absorption resistance.

The zirconium alloy contains, by weight, 0.01-0.2% Ni and 0.1-1.5% Nb, and further, the atomic concentration ratio between Nb and Ni which are contained in precipitated secondary phases, Nb/Ni, is regulated to 0.5-2.0. Moreover, the average grain size of the grains of the secondary phases precipitated in the alloy is regulated to ≤0.20μm. Further, this alloy contains, by weight, one or more kinds among 0.5-2% Sn, 0.03-0.2% Cr, or 0.10-0.3% Fe.