To provide an air cleaner capable of easily mounting and demounting a filter into/from a case.

The cylindrical filter 20 is stored in the case 11 of the air cleaner, and a seal ring 21 is laid between inner faces of both end plates 12b, 13b of the case 11 and end face plates 20b, 20c of the filter 20. The seal ring 21 includes a joint face 23a joined to the inner faces of the end plates 12b, 13b of the case 11, a stopper 24 corresponding to the end face plates 20b, 20c of the filter 20 so as to abut thereon, and an annular seal part 25 provided at the outer periphery side of the stopper 24 and protruded to the filter 20 side beyond a stopper face 24a of the stopper 24 to be joined to the end face plates 20b, 20c of the filter 20 to seal a space between the inside and the outside of a joint portion.