A seat-occupancy sensor with a base state and a switched state, wherein the seat-occupancy sensor consists of a housing, a switching knob that passes through this housing and can move against it, a first electrical contact, a second electrical contact and a disc spring located in the housing, this disc spring having a concave side, a convex side, an outer edge and an inner edge, and wherein the disc spring further has an initial state and can be put into a snapped-through state, and the first electrical contact and the second electrical contact are routed out of the housing, with the first electrical contact and the second electrical contact facing the concave side and the switching knob facing the convex side of the disc spring, and the outer edge of the disc spring being supported on its concave side in the housing, characterized in that the disc spring has a mechanical connection with an electrically conductive switching reed, a part of the switching reed assigned to the first electrical contact is electrically connected to the first electrical contact in both the base state and the switched state, and in the base state, the disc spring is present in its initial state and the second electrical contact is electrically isolated from the part of the switching reed assigned to the first electrical contact, and in the switched state, the switching knob is supported on the inner edge of the disc spring, the disc spring is present in its snapped-through state and the second electrical contact is electrically connected to the part of the switching reed assigned to the first electrical contact, and that the switching reed consists of a first spring element and a second spring element, and that the part of the switching reed assigned to the first electrical contact is the first spring element and the part of the switching reed assigned to the second electrical contact is the second spring element, and that one end of the first spring element and one end of the second spring element are in fixed positions in the housing, and that in the base state, the first and the second spring elements (19, 20) are electrically isolated from one another, and in the switched state, the switching knob rests on the first spring element and the first spring element is supported on the second spring element. characterized in that the disc spring has a mechanical connection with an electrically conductive switching reed, a part of the switching reed assigned to the first electrical contact is electrically connected to the first electrical contact in both the base state and the switched state, and in the base state, the disc spring is present in its initial state and the second electrical contact is electrically isolated from the part of the switching reed assigned to the first electrical contact, and in the switched state, the switching knob is supported on the inner edge of the disc spring, the disc spring is present in its snapped-through state and the second electrical contact is electrically connected to the part of the switching reed assigned to the first electrical contact, and that the switching reed consists of a first spring element and a second spring element, and that the part of the switching reed assigned to the first electrical contact is the first spring element and the part of the switching reed assigned to the second electrical contact is the second spring element, and that one end of the first spring element and one end of the second spring element are in fixed positions in the housing, and that in the base state, the first and the second spring elements (19, 20) are electrically isolated from one another, and in the switched state, the switching knob rests on the first spring element and the first spring element is supported on the second spring element.