The present air cleaner includes: a cleaner case having a bottom wall, a circumferential side wall provided with an air inlet in its lower part, and a support wall formed on the bottom wall inside the circumferential side wall; and a cylindrical cleaner element supported on an upper end portion of the support wall. An air chamber is defined by the cleaner case, the support wall, and the cleaner element so as to surround the cleaner element and the support wall. A bottom of the cleaner element is inclined at an angle to the bottom wall of the cleaner case so that a distance between the bottom wall of the cleaner case and the bottom of the cleaner element increases from a side opposite to the air inlet toward an air inlet side.