This paper aims to develop the method for identifying human and environmental impedances with information in the frequency domain by using bilateral control system. In the conventional method, a sinusoidal wave is added to the common mode of bilateral control system, however, this method cannot extract haptic information in frequency domain. Human impedances are assumed to change every moment, and the identification method of impedance is strongly desired to develop. In this paper, low-pass filtered M-sequence signal is added to the bilateral control system for identifying both human and environmental impedances with information in the frequency domain. Experiments were conducted for verifying the effectiveness of the proposed method.