Abstract: An echo canceller comprises an adaptive digital filter and a low frequency component suppresser. The canceller is used for two-wire full duplex digital data transmission system. The adaptive filter comprises a transversal filter with plural number of taps for generating an echo replica signal by adaptively estimating the time-varying transfer characteristics of an echo path in order to suppress the echo signal from the echo path. The low frequency component suppresser is installed in parallel with the adaptive filter to effectively increase the number of taps of the transversal filter, and to suppress the level of the low frequency component contained in a residual echo signal which is the difference between the echo signal and the echo replica signal at tail portion of the impulse response of the echo replica signal. Due to the low frequency component suppresser, the number of taps of transversal filter is considerably decreased and the arithmetic operation is greatly reduced.