An austenitic stainless steel improved in creep strength, creep ductility, weldability and also hot workability. The steel, consisting of, by mass %, C: 0.05-0.15%, Si: not more than 2%, Mn: 0.1-3%, P: 0.05-0.30%, S: not more than 0.03%, Cr: 15-28%, Ni: 8-55%, Cu: 0-3.0%, Ti: 0.05-0.6%, REM: 0.001-0.5%, sol. Al: 0.001-0.1%, N: not more than 0.03%, and the balance being Fe and incidental impurities. This steel may contain one or more of Mo, W, B, Nb, V, Co, Zr, Hf, Ta, Mg and Ca. It is preferable that REM is Nd.