To stably cancel noise by always updating the coefficients of a noise control filter, that synthesizes pseudonoise, properly in a feedback type active noise controller which generates pseudonoise having same amplitudes and inversed phases of the noise to be muffled from a speaker to cancel the noise.

The controller is provided with an inverse filter constituting circuit 260 which provides an inverse characteristic to the input signals of a noise control filter (220), and a system identifying circuit 120 which gives two sets of different coefficients to the filter (220), obtains a computational equation to compute the coefficients of the filter (220) from two conditional equations by the transfer function of the filter located in the circuit 260 and updates an adaptive filter 123 so that the difference between the output of a first filter 121 that constitutes the numerator of the computational equation and the output of the filter 123 that is cascade connected to a second filter 122 that constitutes the denominator of the computational equation becomes a minimum. Then, the coefficients of the filter 123 are set to the coefficients of the filter (220) and compensation is made for a minimum delay of an acoustic feedback system.