According to this structure, water flowing through the first channel portions 61 from the second outlet 72 side toward the first outlet 71 side is likely to enter the second channel portions 62. However, in the present embodiment, the second outlets 72 are located at a position higher than the boundary portions of the first case body 10 and the second case body 20 as described above, and therefore water is not likely to intrude through the second outlets 72. Also, the projection portions 22 that reduce the size of the openings of the second spaces S2 are provided in the second case body 20, thus making it less likely for water to intrude into the space portions 613 of the first channel portions 61. In other words, the intrusion of water from the second outlet 72 side of the first channel portion 61 is suppressed, and therefore little water flows in from this direction.

In this way, according to the structure of the connection portion between the first channel portion 61 and the second channel portion 62 of the present embodiment, a certain amount of water is predicted to intrude from the first outlet 71 side, and even if water intrudes from the first outlet 71 side, that water is directly drained from the second outlet 72. The intrusion of water from the second outlet 72 side can be prevented to a certain extent by the shape of the second outlet 72 and the provision of the projection portions 22, and therefore it is not a big problem if the structure of the connection portion between the first channel portion 61 and the second channel portion 62 does not take this intrusion of water into account.