An air cleaner (36) mounted on a motorcycle for purifying an engine intake air (A) includes a lower casing (50) forming a cleaner main body, a covering (51) for covering an upward region of the lower casing (50), a cleaner element (55) disposed inside the lower casing (50) and positioned below a mating interface (53) between the lower casing (50) and the covering (51), and a partition wall (57) formed in the lower casing (50) for supporting the cleaner element (55) and forming a part of a wall of a clean chamber (58).
