An Fe-Ni-Cr-base superalloy essentially consists of, by weight, up to 0.15 % C, up to 1.0 % Si, up to 3.0 % Mn, 30 to 49 % Ni, 10 to 18 % Cr, 1.6 to 3.0 % Al, one or more elements selected from Groups IVa and Va whose amount or total amount is 1.5 to 8.0 %, and balance of Fe and unavoidable impurities. If necessary, Mo, W, Co, B, Mg, Ca, Y and REM can be added in predetermined ranges. The superalloy is suitable for engine valves, knitted mesh supporters for exhaust gas catalyzers and so forth, and is excellent in high-temperature strength and normal-temperature ductility after long-time heating and has a sufficient acid resistance property.