Abstract: An apparatus and a method for monitoring an elevator door include a sensor for detecting three-dimensional image information. Processing equipment evaluates the image information of detected images to recognize a deviation between two images and trigger a situation-adapted reaction. The sensor includes a light source mounted in the region of the elevator door so that the elevator door is disposed at least partly in the illuminated region of the light source. In addition, the sensor includes a sensor group mounted so that it receives light reflected from the door.