To produce a Cr-Mo seamless steel pipe free from the dispersion of strength and excellent in toughness by a simplified producing process.

In the case of heating a billet contg. 0.10 to 0.25% C, ≤1.0% Si, 0.2 to 2.0% Mn, ≤0.020% P, ≤0.010% S, 0.2 to 1.5% Cr, 0.1 to 0.5% Mo, 0.005 to 0.020% Ti, 0.01 to 0.10% V and ≤0.006% N, if required, contg. one or ≥ two kinds among ≤1.0% Ni, ≤0.5% Cu and ≤0.01% Nb and the balance Fe with inevitable impurities, punching rolling the billet and thereafter, finish rolling composed of drawing and sizing the billet, under the condition of ≥900°C finishing temp., large working distortion is provided by finishing the billet at ≥40% reduction rate in the cross section area. Moreover, after the finish rolling, without executing cooling, the billet is directly soaked to the temp. range of 900 to 1,000°C, quenched and tempered so that the heat treatments are continuously executed online.