A monitoring device for a disk brake includes a sensor configured to be attached to a brake caliper of the disk brake; and a measuring element configured to be moved relative to the sensor unit. The sensor is designed to register a relative position of the measuring element. The sensor and the measuring element are spaced from one another for the purpose of forming a contactless monitoring device. The preloading element is arranged between the measuring element and the sensor for preloading the measuring element against a pressure spindle of the disk brake.