A charging device of a hearing aid has a charging unit, which has a housing with a housing cover and a magnet arranged therein and movably guided in a longitudinal direction. At one longitudinal end, a contact is attached on the magnet for the detachable, direct electrical contacting with a counter contact of the hearing aid. The contact is electrically connected by a line to a charging circuit, wherein the housing cover has an opening, within which the contact is inserted. The charging device is part of a system having a hearing aid.