To obtain an apparatus for cancelling a noise capable of further enhancing followability by introducing a forgetful coefficient for deciding a weight of past data and adaptively controlling the coefficient.

The apparatus for cancelling the noise comprises adaptive filters 52, 53 for generating pseudo-noise signals having a correlation with a noise component mixed with an information signal based on energy waves from energy wave generating means 41, 43 and 44, subtracting means 26, 27 for subtracting the noise signal from the information signal to obtain an information signal in which a noise component is cancelled, and variable gain means 32, 33 for varying a step gain and the forgetful coefficient in the apparatus for cancelling the noise. The variable gain means is controlled by a control means 46 for controlling a drive signal source.