PURPOSE: To prevent muddy water from entering a canister and facilitate a canister installing operation by inserting the drain part of said canister into the opening part of a through a grommet and introducing it out of an engine room.

CONSTITUTION: A canister 11 consists of a canister body 12 and a canister drain 13. With the drain part 13b being inserted into the opening part 15c of the horizontal placing surface part 15b of a hoodredge 15 through a grommet 16 and introduced out of an engine room E, the canister 11 is supported by the vertical wall part 15a of the hoodredge 15 via a mounting bracket 14. In the grommet 16, the opening peripheral part 15d of the hoodredge 15 is fitted into its fitting groove 16a while the drain part 13b is inserted into its inserting hole 16b, and a cylindrical partition part 16c is extended downward so as to enclose the drain part 13b.