An air cleaner has a casing body having an opening that communicates with a carburetor. The casing body includes a fitting part having an inner wall surface and a bearing surface. A sealing frame is inserted into the casing body and engages the fitting part of the casing body. The sealing frame has an outer peripheral part with an outer peripheral surface that is held in contact with the inner wall surface of the fitting part, a rear surface that is held in contact with the bearing surface of the fitting part, a front surface, and a groove formed in the front surface along a circumference thereof. A filter is disposed internally of the sealing frame. A cover covers the filter and the sealing frame.