The present invention relates to an Fe—Ni-based alloy having excellent high-temperature characteristics and hydrogen embrittlement resistance, which has a composition containing, in terms of % by mass, C: 0.005% to 0.10%, Si: 0.01% to 0.10%, P: 0.015% or less, S: 0.003% or less, Ni: 23.0% to 27.0%, Cr: 12.0% to 16.0%, Mo: 0.01% or less, Nb: 0.01% or less, W: 2.5% to 6.0%, Al: 1.5% to 2.5%, and Ti: 1.5% to 2.5%, the balance being Fe and other unavoidable impurities.