The invention is directed to a modular hearing aid device having a microphone module that comprises a microphone module housing and at least one microphone, and having a hearing aid device module that comprises a hearing aid device module housing, whereby the microphone module housing supplements the hearing aid device module housing to form a housing of the hearing aid device having a uniform effect, and whereby the microphone module and the hearing aid device module are detachably connected, and whereby the hearing aid device module comprises at least one microphone.