A common component extraction unit extracts a component Mi(n) included commonly in the plural input channels. A non-common component extraction unit extracts a component Si(n) not common to the plural input channels. A common component noise suppression unit obtains signal Mo(n) by executing a noise suppression process for the component Mi(n). A non-common component processing unit obtains signal So(n) by executing attenuation or emphasis for the component Si(n). A plural-channel generation unit removes noise of the common component from signals In(n, k) of the plural input channels, by using the signals Mo(n) and So(n) such that the non-common component is attenuated or emphasized.