Abstract: An instrument for measuring a thickness of a surface processing film on a metal includes a plurality of instruction executing keys, an enclosed recording apparatus, a terminal for connecting a probe to detect an electrical signal corresponding to the film thickness when the probe is pressed onto the metal, a circuit for converting the electrical signal obtained from the probe to a digital value indicative of the film thickness, and a circuit for arithmetically processing the digital value in accordance with instructions by the instruction executing keys. The results of the processing are outputted to the recording apparatus.