A splash guard mechanism for preventing the entry of grass, in addition to mud and gravel, in a vehicle such as a an ATV (All Terrain Vehicle). A disc-shaped splash guard mechanism covers a brake disc stored in a concave portion of a wheel to thereby prevent the entry of dirt such as mud, gravel, and grass into the brake disc. If the dirt enters the brake disc, the dirt is ejected from a first cutout portion provided on a lower portion of the splash guard mechanism. Additionally, a grass removal portion substantially triangle-shaped in plan view is provided on a lower portion of the splash guard mechanism. The grass removal portion protrudes toward a vehicle center to push grass on the ground outward and away from the first cutout portion. Since the grass is only pushed out, the grass is prevented from being cut and entering the brake disk.