In a vehicle for off-road use, an engine is mounted on a lower portion of a body frame, a carburetor is attached to the engine, and a main air cleaner is attached to the carburetor. The carburetor is provided with an air vent unit attached thereto, for transferring atmospheric pressure to fuel in a float chamber in the carburetor, and a supplemental air cleaner is attached to the tip of the air vent unit. The supplemental air cleaner is disposed above the engine, and above and anterior to the carburetor and the main air cleaner. Since the supplemental air cleaner is substantially covered, from below, by the internal combustion engine, the carburetor, and the main air cleaner, fluids splashed up from a road surface can be blocked by these components, so that the supplemental air cleaner is substantially prevented from being exposed to splashed fluids.