Disclosed is an austenitic stainless steel which comprises the following components: C: 0.04-0.18%, Si: 1.5% or less, Mn: 2.0% or less, Ni: 6-30%, Cr: 15-30%, N: 0.03-0.35%, and sol.Al: 0.03% or less, and which further comprises at least one component selected from 1.0% or less of Nb, 0.5% or less of V and 0.5% or less of Ti, with the remainder being Fe and impurities, wherein the impurities contain the following components: P: 0.04% or less, S: 0.03% or less, Sn: 0.1% or less, As: 0.01% or less, Zn: 0.01% or less, Pb: 0.01% or less and Sb: 0.01% or less, and wherein the following formulae are fulfilled: P1 = S+[(P+Sn) / 2]+[(As+Zn+Pb+Sb) / 5] = 0.06; and 0.2 = Nb+2(V+Ti) = 1.7-10xP1. The austenitic stainless steel has high strength and, when used in a welded part, can exhibit excellent embrittlement crack resistance during being used at a high temperature. The steel is suitable as a material for an instrument that is intended to be used at a high temperature for a long period, such as a boiler for power generation.