Monitoring apparatus for monitoring a movement element pivoted between open and closed states of an opening to be closed, the apparatus having a sensor for detecting an object and for monitoring a spatial angle originating at or near the rotation axis. The sensor is fitted at or near the rotation axis and includes a transmitter and receiver for transmitting and receiving radiation within the spatial angle. The sensor emits detection signals generated by the receiver when radiation is detected. The monitoring apparatus includes an evaluation unit that evaluates the detection signals depending on the angular position of the detected radiation in the spatial angle and determines whether an object has been detected and/or the position of the detected object. The evaluation unit draws a distinction between the movement element and an object depending on the current angular position of the movement element.