In this paper, a DCT-based lossy haptic data compression method for a haptic communication systems is proposed to reduce the data size flowing between a master and a slave system. The calculation load for the DCT can be high, and the performance and the stability of the system can deteriorate due to the high calculation load. In order to keep the system a hard real-time system and the performance high, a fast calculation algorithm for DCT is adopted, and the calculation load is balanced for several sampling periods. The time delay introduced through the compression/expansion of the haptic data is predictable and constant. The time delay, therefore, can be compensated by a time delay compensator. Furthermore, since the delay in this paper is small enough, stable contact with a hard environment is achieved without any time delay compensator. The validity of the proposed lossy haptic data compression method is shown through simulation and experimental results.