PURPOSE: To cause a slip between a mandrel and a blank, in order to disperse the wall thickness deviation all over the circumference of the work, by giving a different rotational speeds respectively to the mandrel and the cylindrical body, at forming a cylinder by pressing a roll to the cylindrical work rotating together with the mandrel.

CONSTITUTION: The tail spindle 3 is retreated, and the blank W is inserted into the mandrel 1 through the space formed between the tail spindle 3 and the mandrel 1. Next, the tail spindle 3 is fed forward to longitudinally press the work W to the mandrel 1 through the bearing 6. Then, the mandrel 1 and the tail spindle 3 are rotated at respectively different speed in order to cause a specified slip between the speeds of said W and the mandrel 1. Hereupon, the roll 5, for giving a specified rolling reduction, is pressed to the surface of said W, and at the same time, the roll 5 is transferred along the axis of the mandrel 1. Hereby, said W, while causing a slip in its circumferential position against the mandrel 1, is formed in the direction of axis of the mandrel 1 into a cylinder having a uniform wall thickness.