Disclosed herein is an ear canal fitting unit including: a tube configured to be capable of being inserted into an ear canal an electrode configured to have flexibility and be so disposed along an outer circumferential surface of the tube that a predetermined gap is formed between the electrode and an inner surface of the ear canal pressing means for deforming the electrode in such a direction as to get away from the outer circumferential surface of the tube and pressing the electrode against the inner surface of the ear canal and suppressing means for suppressing push-back of the electrode pressed against the inner surface of the ear canal.
