Time delay in bilateral teleoperation systems is inevitable and very serious problem. It possibly destabilize systems and deteriorates the performance of systems. Many researches about time delay in bilateral teleoperation systems have been proposed so far. In such a situation, authors have proposed a time delay compensation method based on the concept of network disturbance (ND) and communication disturbance observer (CDOB). It can stabilize time delayed bilateral systems. Furthermore since the method does not need delay time model, it is applicable to the case with time-varing or fluctuant time delay like that of Internet. In this paper, a new design method (or condition) of cutoff frequency of low pass filter (LPF) in CDOB considering approximated poles of ND is proposed. The validity of proposed design method (or condition) is verified by simulation results.