Pseudo space transmitting signal processing means of the signal processing means simulates the frequency response of the space up to the silencing point from a noise source, while pseudo inverse filter signal processing means simulates an inverse filter characteristic 1/(K.times.Sp.times.G1) for canceling the characteristic of the combined frequency response (K.times.Sp.times.G1) of K of noise input means, Sp of a secondary sound source speaker, and G1 up to a silencing point from a secondary sound source speaker. The pseudo space transmitting signal processing means and pseudo inverse filter signal processing means set a gain characteristic equal to an original space transmitting characteristic and inverse filter characteristic, respectively. Moreover, the pseudo space transmitting signal processing means is structured to provide a delay of phase for an amplitude characteristic, while the pseudo space transmitting signal processing means is structured to lead the phase as much as a delay of the pseudo inverse filter signal processing means. Thereby, the present invention can provide an active silencer comprising signal processing means for generating signal for canceling noise and having a stable filter characteristic.