To provide a connection pipe with improved cleaning efficiency.

A suction passage 47 and an exhaust passage 48 equipped in parallel are separated by a partition wall 45. The inner wall seal part 56 of a seal ring 54 is attached to the end part downstream to the exhaust passage 48 on the partition wall 45. A connection acceptor 74 formed by separating the suction port 75 and the exhaust port 76 by another partition wall 62 is equipped. The suction passage 47b communicates with the suction port 75 and the exhaust passage 48 with the exhaust port 48. The inner wall seal part 56 abuts on the partition wall 62 of the connection acceptor 74. The inner wall seal part 56 air-tightly connects the partition walls 62, 45. A retaining piece 51 retains the end part downstream to the exhaust passage 46 of the inner wall part 56 in a covered condition. The sectional area of the suction passage 47 is not reduced by the inner wall seal part 56 and the retaining piece 51. Even when air is sucked in the suction passage 47, the inner wall seal part 56 is not rolled up off the partition wall 45. The cleaning efficiency by the suction passage 47 is improved.