A transferring speed-change device is provided between an upstream-side stage and a downstream-side stage which are different from each other in conveying speed and conveying pitch. A speed change pinion is meshed with a transferring rack at the same speed as that of an upstream-side pinion; is maintained at the same speed as that of the upstream-side pinion until a main rack is disengaged from the upstream-side pinion; and is used to drive the carrier after the main rack is disengaged from the upstream-side pinion. The speed change pinion is caused to have the same speed as that of a downstream-side pinion immediately before the main rack meshes with the downstream-side pinion; and is maintained at the same speed as that of the downstream-side pinion until the transferring rack is disengaged from the speed change pinion.