An odor-trap device (1) for in particular flushing-water-free sanitary devices, for example urinals, comprises an outflow element (2) with a sealing wall (3), and also comprises a sealing membrane (4), which is in sealing contact with the sealing wall (3) in a closure position and, in the presence of a liquid, such as urine, is pushed away from the sealing wall (3) from the closure position into an open position, as a result of which a gap (19) is formed between the sealing membrane (4) and sealing wall (3), it being possible for the liquid to be led away through said gap, and further comprises a mounting element (5) for mounting the sealing membrane (4) in relation to the sealing wall (3). The odor-trap device (1) is characterized in that the seating membrane (4) has a seating surface (6) which runs substantially parallel to the sealing wall (3), wherein the sealing surface (6) butts against the sealing wall (3) substantially with surface-area contact, or wherein the sealing surface (6) is spaced apart from the sealing wall (3) such that the liquid film which is present, at least in part, between the sealing wall (3) and the sealing surface (6) provides a force of adhesion between the sealing wall (3) and seating surface (6).