PURPOSE: To facilitate the loading and unloading of a battery and the ON-OFF operation of the battery power source and also to perform the above-mentioned operations on one operation surface of the case body, by providing the battery case of a hearing aid with a hook projection and support axle.

CONSTITUTION: In the main case body, battery case 29 having support axle 35 and hook projection 33 formed in a body is provided being slidable and rotatable. Conseuqently, the ON-OFF operation of the electric power switch and battery replacement can be performed on the same operation surface and the ON-OFF state can be confirmed externally and easily. The battery can be replaced in either ON or OFF mode of the battery power switch and the replacement operation is quickened.