A voice/noise section decision unit 2 makes a decision from a low-frequency amplitude spectrum 102 as to whether an input signal 100 is like a voice or not. A noise spectrum estimation unit 3 estimates a low-frequency noise spectrum and high-frequency noise spectrum from the output of the voice/noise section decision unit 2. A low-frequency processing unit 201 and a high-frequency processing unit 202 perform noise suppression based on the noise spectrum output from the noise spectrum estimation unit 3.