A counter 160 increments a count value every given period. An adaptive operation control unit 90 selects channels in.which adaptive operation are done from all the channels in obedience to the count value to output produced selection signals to AND circuits 151 to 15n. Double-talk detection circuits 81 to 8n judge the presence of double-talk states and output detection signals to the AND circuits. The AND circuits operate logical AND of the selection signals and the detection signals and output the logical AND results as control signals to filter coefficient updating circuits 71 to 7n. The filter coefficient updating circuits update or do not update filter coefficients stored in FIR filter units 51 to 5n according to the control signals. The FIR filter units produce echo replicas by calculating convolutions of the filter coefficients and the receive signals. Subtractors 61 to 6n subtract the echo replicas from transmission signals to output residual signals.
