To provide an acoustic device capable of suppressing the influence due to noise.

The acoustic device includes a first amplification means 23 and a sound signal control means 22 for controlling sound signals input from a sound source 21 to the first amplification means 23. When an amplifier unit 30, having a second amplification means 33, is connected to the output destination of the first amplification means 23, the sound signal control means 22 is stopped from executing control of making the level of the sound signals input from the sound source 21 to the first amplification means 23 be lower than the output level of the sound source 21, and control contents which are to be executed to the sound signals by the sound signal control means 22 are transmitted to the amplifier unit 30.