A holding region (41) includes a first area bearing on at least part of one and at least part of the other of opposite skirt portions in a revolution direction of a holding pad (40), the first area extending along a first curve (P1), when the holding pad (40) is at a first revolution position (E1). The holding region (41) formed in the holding pad (40) includes a second area bearing on at least part of one side portion and at least part of the other side portion in the revolution direction of the holding pad (40) when the holding pad (40) is at a second revolution position (E2) that extends along a second curve (P2). The holding region (41) includes a portion other than the first area and the second area that lies closer to a second rotational axis (C2) than the first curve (P1) and the second curve (P2).
