PURPOSE: To obtain a satisfactory noise removing effect by dividing an input signal into a low frequency component and a high frequency component and, at the arrival of a noise, by processing the former component by integrating interporation system and interrupting the later component.

CONSTITUTION: An input signal is emphasized at its noise component by a preemphasis circuit 2 and delayed by a delay time T1 exceeding noise time width in a delay circuit 3. An output of the circuit 3 is separated by an LPF4 and an HPF5 and the separated outputs are inputted to delay circuits 9, 13 respectively to make the signals delay by time T2. An output of the circuit 3 is also inputted to a control circuit 8 after removing its noise by a BPF6 and a noise detecting circuit 7. The input and output signals of the circuit 9 are subtracted by a subtractor 10 to find the level difference between before and after the leading edge of a noise and then inputted to an integrating circuit 11. At the detection of a noise, the circuit 8 controls the interrupting frequency fC of the LPF4 and then controls the circuit 11, a sample holding circuit 12 and a gate circuit 14, so that the low frequency component is processed by integrating interpolation and the high frequency component is outputted by breaking the circuit 14 and adding the outputs of the circuits 12, 11 by an adding amplifier 15. At the absence of a noise, the circuit 14 is made and the output of the circuit 14 is added to an output of the circuit 12 by the amplifier 15.