PURPOSE: To measure not only a zone within the range where an oscillation amplitude is approximately in proportion to a distance, but also a zone exceeding the range.
CONSTITUTION: This range finder is equipped with an eddy current sensor 10 having a coil, and an amplifier unit 12 for amplifying an output signal from the sensor 10, and measures a distance from the reference position of a measuring object formed out of such a material as generating eddy current due to high-frequency current flowing to the coil. Furthermore, the device includes a converter 14 for converting such an analog signal from the unit 12 as generated with the flow of the eddy current and corresponding to the loss thereof, into a digital signal, and a controller 16 for saving a relationship between the digital signal and the distance in advance and selecting such a distance as corresponding to the digital signal, upon receipt thereof from the converter 14.