Provided is an Ni-base alloy excellent in strength, ductility and other properties through the resolution of micro-segregation. Also provided is a process for manufacturing an Ni-base alloy containing by mass C: 0.15% or less, Si: 1% or less, Mn: 1% or less, Cr: 10 to 24%, Mo+(1/2)W (where Mo may be contained either alone or as an essential component): 5 to 17%, Al: 0.5 to 1.8%, Ti: 1 to 2.5%, Mg: 0.02% or less, and either B: 0.02% or less and/or Zr: 0.2% or less at an Al/(Al+0.56Ti) ratio of 0.45 to 0.70 with the balance consisting ofNi and impurities, which comprises subjecting, at least one time, an Ni-base alloy raw material which is prepared by vacuum melting and has the above composition to homogenization heat treatment at 1160 to 1220°C for 1 to 100 hours. The Mo segregation ratio of the alloy is controlled to 1 to 1.17 by the homogenization heat treatment.