The optical frequency of an optical frequency comb can be expressed as a frequency in the microwave band and is called the scale of light. Applications such as distance measurement and gas concentration temperature measurement using an optical frequency comb have been developed. However, optical comb devices are expensive laser transmitters, and it is difficult to conduct research using commercially available products. In this study, distance was measured using an inexpensive optical comb. The laser emitted from the optical frequency comb was split into two optical paths by a half mirror and entered a detector, and the phase difference caused by the difference in the two optical paths was measured. After moving one of the detectors to change the optical path length, the phase difference was measured again. The difference between the two-phase differences was calculated, and the travel distance of the detector was calculated from this value. To measure the phase difference, a preamplifier, a double-balanced mixer, a frequency doubler, and a lock-in amplifier were used. Since the frequency used in the measurement was too high to be locked in was difficult, a double-balanced mixer and a frequency doubler were used to beat down the electrical signal and measure the phase difference. In addition, to perform stable measurements, a signal was generated from the lock-in amplifier and the phase difference with that signal was measured, simplifying the lock-in and measurement.