In the present invention, a bead core formation device is provided with the following: a rubber covering device that covers the outer peripheral surface of a steel wire with rubber; and two cooling rollers (71, 80) on which rubber-covered lines (110), which are steel lines (110) covered in rubber, are wound. The second cooling roller (80) is provided with a first groove (82A), and a second groove (82B) on which a portion of the rubber-covered line (110) downstream from the first groove (82A) is wound. A diameter LB in a portion where the second groove (82B) is formed is smaller than a diameter LC in a portion where the first groove (82A) is formed.