To provide a method for manufacturing an austenitic stainless-steel pipe for a heat exchanger superior in corrosion resistance under a severely corrosive and hot environment.

The method for manufacturing the austenitic stainless-steel pipe for a heat exchanger superior in corrosion resistance is characterized by; reheating steel which includes 0.03% or less C, 2.0-4.0% Si, 0.7% or less Mn, 22-25% Ni, 24-30% Cr, 1.0-2.0% Mo, 0,2% or less N, 0,1-0.30% Nb, by mass%, and the balance Fe and impurities, and of which the Ni-bal. expressed in the following expression is 0.5-3.5, at 1000°C or more; keeping the temperature; and immediately quenching it to about 600°C at a speed of 30°C/second or higher to control carbide precipitation in a grain boundary. Ni-bal.=Ni+27C+23 N+0.2Mn-1.2(Cr+Mo)-0.5Si-0.3Nb+10.