A noise cancellation system with improved performance for canceling from an input signal of a microphone a noise component relating to reproduced sound of an audio system reproducing multiple channels of sound, provided with an audio canceller for acquiring audio signals of two channels and processing them by filter coefficients by convolutional processing so as to produce noise cancellation signals at adaptive filters, an adder for adding the input signal of the microphone and the noise cancellation signals, canceling the noise component from the input signal, and outputting the signal after noise cancellation, nonlinear converters for nonlinear conversion of the signal after noise cancellation, and filter learning units for calculating the filter coefficients to be set next based on the nonlinear converted signal.