The invention relates to a method for monitoring a CMP polishing method, a substrate being fixed in a mount, a polishing pad being fixed on a plate, a surface of the polishing pad being operatively connected to a surface of the substrate, the polishing pad and the substrate being moved relative to one another, so that material is removed from the surface of the substrate. A measuring device is provided, which is operatively connected to the surface of the polishing pad, the measuring device detecting the surface constitution of the polishing pad and generating a measurement signal dependent on the surface constitution of the polishing pad. The measurement signal is compared with corresponding reference values for the purpose of identifying a change in the material of the surface of the substrate during the CMP polishing method.