Ear canal fitting unit and a biological signal measuring device

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.