PURPOSE: To prevent generation of a shoe mark by deviating the axial center of a rolling plug always to a specified extent in the direction of any one guide shoe side.

CONSTITUTION: The rotating speed of at least either one of driving motors 10, 11 is controlled to increase or decrease by 2W3% with respect to a reference value to apply a difference to the peripheral speeds of two rolling rolls 1, 2 of a cross helical rolling mill prior to biting of a blank pipe 3 to the space between the two rolls 1 and 2. The rolling plug 7 is so arranged that the axial center 7a thereof deviates always to a specified extent toward either one side of the guide shoes 4, 5 at the time when the blank pipe 3 bites into the space between the rolls 1, 2. The rolling torques of the motors 10, 11 are detected after the pipe 3 is bitten between the rolls 1 and 2 and the rotating speed of at least either one of the motors 10, 11 is so controlled that the rolling torques are made equal.