To produce a heat resistant austenitic stainless steel having sufficient structural stability as well as high strength at high temperature, excellent steam oxidation resistance, and excellent fire side corrosion resistance.

This steel has a composition consisting of by mass 0.04-0.10% C, ≤0.4% Si, ≤0.6% Mn, 20-27% Cr, 22-32% Ni, ≤0.5% Mo, 0.20-0.60% Nb, 0.4-4.0% W, 0.10-0.30% N, 0.002-0.008% B, 0.003-0.05% Al, further at least either of <0.010% Mg and <0.010% Ca, and the balance Fe with inevitable impurities. The steel can be suitably used for boilers working at high temperatures.