In a vehicle having an air cleaner for cleaning incoming intake air supplied to an engine, a stepped surface is formed on at least one of a plurality of walls of an air cleaner housing. The stepped surface is formed on an upper wall of the air cleaner housing, such that an outer step is arranged on a periphery of an inner step. The upper wall is formed into a stereoscopic shape by providing the stepped surface thereon, such that the rigidity of the upper wall is enhanced, and a sonic resonance of the upper wall can be suppressed during vehicle operation, thereby reducing intake noises. By providing the stepped surface to the upper wall of the air cleaner for reducing intake noises, and it is unnecessary to add one or more extra components to the air cleaner for reducing intake noises.