Abstract: An active vibration controller includes acceleration detectors for generating output signals on the basis of vibrations of a vehicle, speakers provided in a vehicle's cabin, microphones provided in the vehicle's cabin for receiving generated sounds from the speakers and road noises generated on the basis of running of the vehicle, and adaptive digital filters using output signals from the acceleration detectors as inputs for controlling filter factors on the basis of an RLS algorithm to minimize levels of output signals from the microphones in response to output signals from the microphones and output signals from the acceleration detectors through use of a transfer function matched to the transfer function of the vehicle's cabin in a sound field between the speakers and the microphones. The controller minimized levels of output signals from the microphones by developing an applied output signal to the speakers.