PURPOSE: To reduce the cost and power consumption by cancelling sufficiently a low level acoustic echo component without lots of high speed arithmetic operation processing for an echo canceller, to realize it without a remarkable circuit revision and circuit addition, and to improve the naturality of talking by stopping clipping when a reception sound volume is small even in the reception state.

CONSTITUTION: A center clipper 36 is provided on an output of an adder 32 in an echo canceller 30. The operation of the center clipper 36 is controlled by a control circuit 4 based on transmission reception state detection information DES detected by a comparator 53 and a detector 54 provided in a voice switch circuit 50 and a sound volume adjustment level by a variable resistor 23.