The invention concerns a hearing aid comprising: an outer housing (1) containing a signal processing module (11) connected in input to at least a microphone (13) and in output to an earphone for transmitting a sound signal into the patient's external auditory canal (5); at least one first magnetic component (12) arranged in the outer housing (1); at least one second magnetic component (21) arranged in an implantable housing designed to be implanted under the patient's skin, at a site where the outer housing (1) can be maintained, the first magnetic component being arranged in the outer housing such that a magnetic attraction force is exerted with the second magnetic component when the outer housing (1) is placed at said site; and a device for delivering sound signals into the patient's external auditory canal comprising the earphone and a connection (4) between the outer housing (1) and the auditory canal.