A silicon micromechanical non-reverse valve. In a main surface of a silicon wafer there is provided a cavity and a cantilever beam. The beam extends over the cavity and is integrally formed with the wafer at its top portion. The beam is provided at a distance above the bottom wall of the cavity. A second wafer of silicon or glass is provided over the first silicon wafer and covers the cavity in order to form a chamber. A second wafer is provided with two openings one of which is situated within the outline of the beam and the other of which is situated outside said outline. The first opening acts as an inlet and the second opening as an outlet for the valve.
