A coupling lock for a trailer coupling. The coupling lock comprises a receptacle (9) in which a coupling element (6) is inserted, an angle measuring device (13, 19) is connected to the receptacle (9), and the angle measuring device (13, 19) is provided for detecting rotation of the receptacle (9), about a rotational axis (18), relative to the coupling element (6). A magnetically adhering body (24) is elastically connected to the receptacle (9) and magnetically connectable to the coupling element (6) for actuating the angle measuring device (13, 19).