A device for detecting the weight loaded on a vehicle seat with a sensor (22) and a spring body (24) that connects the vehicle seat to an underbody (18) of a corresponding motor vehicle and is connected, in one fastening area (e.g., 28), with a bottom rail (20) of the vehicle seat on the one hand and, in another fastening area (e.g., 26), to the underbody (18) of the corresponding motor vehicle on the other hand. One of the mounting areas is provided with a bore (38) through which a seat fastening screw (30) is engaged. The sensor (22) is provided with a travel sensor which is disposed parallel to the seat fastening screw (30) between the two fastening areas (26, 28) or to these rigidly connected parts (retaining plate 60 for example) and which measures the distance of these fastening areas (26, 28) parallel to the seat fastening screw (30).