A device for filtering the intake air of an internal combustion engine having an expansion box (110) with an opening (12) for the intake air to pass therethrough, has a filter fixed to the opening that includes a first tubular filtering element having an upper annular element (1) having an upper end of the first tubular filtering element fixed thereto. A second filtering element is peripherally fixed to the upper annular element, over an upper end of the first tubular filtering element. A lower support (4) has an annular housing (9) for receiving the lower end of the first tubular filtering element therein, and a flat flange (7) for fixing the filter to the expansion box.