A purpose of the present invention is to provide an acoustic apparatus capable of automatically setting a gain which is suitable for both an averaged signal strength of input voice and an instantaneous signal strength thereof, capable of easily recognizing an effect by a user, which is achieved by switching a turn-ON and a turn-OFF of an automatic gain variable operation, and further capable of readily recognizing a change in gain values by the user. The acoustic apparatus is provided with a gain setting unit (20) for setting a gain from an averaged voice strength within a predetermined time period, and another gain setting unit (22) for setting a gain in response to an instantaneous signal strength thereof; and the acoustic apparatus adjusts a signal strength of an audio input signals (Si) based upon a gain “C” obtained by multiplying a gain “A” by another gain “B.”