PURPOSE: To prevent muddy water from entering a canister and facilitate an installing operation by introducing the drain part of said canister out of an engine room through the opening part of a hood ridge and covering this drain part with a cover having a partition part.

CONSTITUTION: A canister 11 consists of a canister body 12 and a canister drain 13. With the canister 11 being supported by the vertical wall part 15a of a hood ridge 15 through a mounting bracket 14, its drain part 13b is inserted into the opening part 15c of the horizontal placing surface part 15b of the hood ridge 15 via a grommet 16, and introduced out of an engine room E. A cover 17 is provided in such a way that it covers the drain part 13b, and splashing muddy water is prevented from entering the inside of the cover 17, mostly being blocked by the vertical wall part 17a and the bottom face part 17d of the cover 17.