PURPOSE: To increase the stability by adding a signal to an output of a delay storage circuit by an adder circuit after a maximum/minimum value of a coefficient calculated by a coefficient correction counter circuit with respect to the correction value so as to reduce the converging speed.

CONSTITUTION: A maximum/minimum value limit circuit 9 limits the maximum/ minimum value calculated by a coefficient correction calculation circuit 8. The adder circuit 10 adds the output of the maximum/minimum limit circuit 9 and the impulse response of the 2nd delay storage circuit 7 and outputs the added output to the 2nd delay storage circuit 7. Thus, the maximum correction of the impulse response is limited, and the converging speed is decreased thereby increasing the stability. Since a small correction is applied while the maximum value and the minimum value are limited, the adaptive operation of the echo canceller is kept constant.