With the hearing aid device of the present invention, when the power is turned on, communication starts between the first and second hearing aids, and until this communication is established, it is recognized that the power has not been switched on to the second hearing aid, and the user is notified. Also, if the battery of the second hearing aid should die during use, a dead battery notification is sent to the first hearing aid, and if communication between the first and second hearing aids is blocked, the user is notified on the side of the first hearing aid that is operating.