A hearing aid includes: a sound collection unit configured to collect a surrounding sound; a sound output unit configured to output a sound; and a main body having a shape that can be attached to an ear. The main body includes: a hearing aid processing unit configured to perform hearing aid processing for the surrounding sound collected by the sound collection unit; an attaching determination unit configured to determine whether the main body is attached to the ear based on the surrounding sound; a specific sound generation unit configured to generate a predetermined signal; and a selection unit configured to select one of the sound subjected to the hearing aid processing by the hearing aid processing unit and the sound generated by the specific sound generation unit based on a determination result of the attaching determination unit and to output the selected sound to the sound output unit.
