Eddy-current (EC) displacement sensors are used in a device for measuring the shaft vibration of turbines. When only the impedance/output voltage (Z/V) converter breaks down, it is necessary to change it with an appropriate Z/V converter by stopping and dismantling the power plant using the discriminant of the sensor probe installed in the neighborhood of the turbine shaft. In this paper, we describe a method for identifying the type of the sensor probe and the displacement x from the measuring object to the coil by measuring the impedance characteristics of the sensor probe.Index Terms-Eddy-current displacement sensor, identification method, maximum quality factor, frequency, displacement.