The present invention relates to an expiratory valve (10) of a ventilation device (100), comprising a valve body (12) having a fluid inlet (14) and a fluid outlet (16) for breathing air of a patient formed therein, said valve body (12) comprising a support (42) having a top side (46) on which a valve membrane (20) can be placed with an abutment area formed at the outer edge thereof, with the top side (46) of the support (42) having an uneven design.
