PURPOSE: To produce the seamless steel pipe having excellent high-temp. strength with a simplified stage by reheating a stock pipe made of a high-Cr steel, subjecting the pipe to finish rolling with specific work strain and air cooling then to a temper heat treatment.

CONSTITUTION: The stock pipe for finish rolling of the high-Cr steel made of the compsn. contg., by weight%, 0.05 to 0.15% C, ≤1.0% Si, 0.2 to 1.0% Mn, 0.02 to 0.15% Nb, 0.09 to 0.30% V, 0.01 to 0.08% N, and 0.1 to 3.0% W, at need is reheated to 850 to 1150°C. The stock pipe is then subjected to the finish rolling in such a manner as to attain ≥0.1 work strain expressed by =ln(Ao/A) where the sectional area of the stock pipe for finish rolling is designated as Ao(cm2) and the area of the finished pipe as A(cm2). The pipe is then subjected to the temper heat treatment at 740 to 820°C after air cooling. The seamless steel pipe which has the high strength and excellent toughness and lends itself to high-temp. applications is obtd. in this way.