A first plate of a filter element includes a first tubular portion having a substantially cylindrical shape that protrudes toward a lid member with the filter element inserted into a filter case. The first tubular portion includes first projections protruding outward in a radial direction. The lid member includes a second tubular portion inserted into a hollow portion of the first tubular portion. With the lid member attached to the first plate, the first projections are inserted into notches formed in ribs provided along an outer circumferential surface of the first tubular portion.