Provided is austenitic stainless steel which has high strength and excellent hydrogen embrittlement resistance, and which additionally has excellent machinability. Austenitic stainless steel according to one embodiment of the present invention has a chemical composition which contains, in mass%, 0.10% or less of C, 1.0% or less of Si, 2.1-6.0% of Mn, 0.045% or less of P, 0.1% or less of S, 8.0-16.0% of Ni, 15.0-30.0% of Cr, 1.0-5.0% of Mo, 0.05-0.45% of N, 0-0.50% of Nb and 0-0.50% of V with the balance made up of Fe and impurities, and which satisfies formula (1). This austenitic stainless steel has a crystal grain size number of less than 8.0 and a tensile strength of 690 MPa or more. 15<=12.6C + 1.05Mn + Ni + 15N (1).