The invention relates to a device and method for detecting the occupation of a seat in a motor vehicle. Said device comprises first sensor elements (SE1), which are flatly arranged on the seat surface of a vehicle seat and are part of a first sensor seat mat (OCSM) for measuring the weight or a weight profile on the vehicle seat. The device also comprises an evaluating unit (A), which is connected down from the sensor elements and provided for evaluating the first sensor signals of the first sensor seat mat (OCSM). The inventive device comprises additional safety sensor elements (SE2), which are flatly arranged on the seat surface of the vehicle seat, likewise connected to the evaluating unit (A), and provided for testing the operability of the first sensor elements (SE1). The inventive device is used in a method for detecting the occupation of a seat in a motor vehicle during which a control unit (S) of an occupant protection system adapts the triggering behavior of an occupant protection means to the determined occupation of the seat when the safety sensor elements (SE2) confirm the weight and/or the weight distribution established by the sensor seat mat (OCSM).