An apparatus for nondestructive, absolute measurement of the properties of solid materials can be derived from the behavior of a body penetrating into the materials, having a guidance device which guides the penetrating body on the surface of the materials and an electrical evaluation circuit. The penetrating body is a probe-tip insert in a single-pole probe set on the material to measure the thickness of thin coatings in the range of several 1000 .mu.m and less. An electrical drive is connected to the guidance device and presses the penetrating body with a specific but variable force onto the surface of the material, and a voltage output by the probe representing the coating thickness is passed on to an evaluating circuit.