To reduce a device cost by changing the coefficient updating frequency of an echo canceller function processing by means of the kind of a voice CODES system to be applied.

An adaptive control part 2ac recognizes transmission voice data DSa outputted from a subtractor 2ae as the difference component of an echo canceller processing immediately before, recognizes reception voice data ARsa added from a data register 2aa as the actual measurement value of pseudo echo voice data PE which is calculated by the echo canceller processing immediately before, executes a prescribed applying control processing for permitting the difference component to get close to zero based on the difference component and the acrual measurement value and updates an arithmetic coefficient to be stored in the coefficient register 2af. When the coefficient updating frequency is set from an external control part, the adaptive control part 2ac executes the updating processing of the arithmetic coefficient in accordance with the set coefficient frequency. When the value of the coefficient updating frequency which is set from the external control part is zero, the updating processing is not executed.