PURPOSE: To obtain a seamless steel pipe with a specified thickness at its pipe end part and stationary part, by making the interstand tension in zero over the whole length of a pipe and performing the reducing with no tension.

CONSTITUTION: A seamless pipe whose thickness is uniform from the pipe end part to stationary part can be manufactured because of the pipe end part thickness of after reducing at each stand being made in a target thickness, in the case of no tension rolling and the yield is improved because of a cropless rolling becoming possible. Also, no offgage is generated by a thinning phenomenon in no tension rolling because of the blank pipe thickness being made larger than the target thickness by the part equivalent to the thinning amount in no tension rolling. Moreover, the elongation length like the thickness becoming constant at the pipe end thickness is found over the whole length of the pipe and the reducing is performed so as to obtain the elongation length, so the reducing at no tension can be facilitated.