Abstract: A device for detecting the state of steel-reinforced concrete construction parts, having one or more sensor wires disposed at different distances from a surface of the concrete construction part. The wires are subjected to the corroding influence of the environment of the concrete construction part. The device also includes a measuring instrument, which measures the volume resistance of the sensor wires and an evaluating device, which can supply the measurement values of the measuring instrument either permanently and/or when called up, and which, evaluating from these values, draws conclusions on the depth-dependent corrosion state of the concrete construction part.