PURPOSE: To obtain a cylindrical body having high roundness by supporting the short-sized cylindrical body by plural longer cylindrical rolls than the body installed so that the axis of the rolls are parallel to each other and pressing the peripheral surface of the body by rolls with the rolls rotated.

CONSTITUTION: A short-sized cylindrical body 1 obtained by cutting is inserted between plural cylindrical rolls 2, 3, 4 so that the axis of the body 1 is parallel with the axises of the rolls 2, 3, 4. Then, the peripheral surface of the roll 2 abuts on the peripheral surface of the body 1 and the rolls 3, 4 are rotated in the direction of the arrow (b) by a driver, so that the body 1 is rotated in the direction of the arrow (c) and the roll 2 rotates in the direction of the arrow (b). If the peripheral surface of the body 1 is pressed by the rolls 2, 3, 4 as the roll 2 gradually approaches the body 1, the peripheral surface of the body 1 is straightened to be a cylinder having high roundness.