To provide a method of manufacturing seamless steel tubes by which the deterioration of surface roughening is deterred without damaging the biting property of barrel-shaped rolling rolls.

This method of manufacturing the seamless tubes is characterized in that the distribution of the quantity of roll cooling water which is supplied to the roll surfaces of the barrel-shaped rolling rolls is set to the distribution in which the cooling capacity in the periphery of a gorge part is raised than the cooling capacity on both inlet and outlet sides. Furthermore, the method is characterized in that the cooling capacity in the periphery of the gorge part is set to 1.3-1.5 times the cooling capacity on both the inlet and outlet sides.