PURPOSE: To simplify a sum of squares calculation, to reduce the calculation amount and to enable processing in real time when a reception signal is normalized, in an echo canceler updating a filter factor by using a learning identifying method.

CONSTITUTION: A reception signal is outputted from a speaker 10, and part enters a microphone 11 via an echo path and part is added to a transmission input signal. A filter 12 estimates the impulse response of the echo path, generates a pseudo echo from the reception signal, adds this echo to the transmission input signal in the opposite phase and cancels the echo. A simplified square sum circuit 15 determines Xn=mXn-1+X2n, where square sum Xn-1 one sample before multiplied by is a constant m (0<m<1) is added to the square X2n of the present reception signal Xn in this square sum calculation, performs a reciprocal calculation 14 for this expression and normalizes the reception signal Xn.