Drainage mechanism and air-conditioning system equipped with same

The purpose of the present invention is to suppress the problem of drain water returning to the drain pan of an air-conditioning indoor unit. A drainage mechanism (60) is connected to a drain pump that sucks up water from the drain pan. The drainage mechanism (60) comprises: a connection portion (62a) connected to the drain pump; a first flow path portion (64); a U-shaped portion (65); and a second flow path portion (68). The first flow path portion (64) extends upward from the connection portion (62a). The U-shaped portion (65) has a first end (65a) connected to the upper end of the first flow path portion (64) and a second end (65b) on the opposite side to the first end (65a). The U-shaped portion (65) changes the direction of the drain water flowing inside from upward to downward. The second flow path portion (68) extends from the second end (65b). The second flow path portion (68) is a pipe having an inner diameter of 13 mm or less. The flow path area of the U-shaped portion (65) is larger than the flow path area of the second flow path portion (68).