In this paper, data compression and decompression method for real-world haptics using discrete cosine transform (nCT) is proposed and applied to a motion copy system. Haptics recently has attracted much interests and been and studied by many researchers. The technology of real-world haptics based on bilateral control systems is expected to apply teleoperation for precise task, education system for human skill, etc. Various researches have been studied for the real-world haptic, haptic data compression for data storage has been not studied much yet. The haptic data is compressed using nCT to reduce the data size. The validity is shown by applying to motion copy system. The data size was reduced less than a quarter, and degradation of decompressed data was little.