An acoustic device includes a rotary operator and a base supporting the rotary operator so that the rotary operator is rotatable. The base includes a braking unit configured to be brought into contact with the rotary operator to cause a braking force to act on the rotary operator and an adjuster configured to adjust the braking force caused by the braking unit. The braking unit includes a plurality of contact members configured to be brought into contact with the rotary operator to cause the braking force to act on the rotary operator. The braking force acting on the rotary operator by the plurality of the contact members varies depending on an adjustment amount by the adjuster.