<p>A brain function detector detects brain function with high accuracy by bringing the forward end part of all electrodes in to contact with the head skin even for different examinees while matching the detector to the individual difference of head part of the examinee. The brain function detector comprises a cap-like detector body to be applied to the head part of an examinee, and a plurality of electrodes fixed at an interval to the detector body so as to be brought into contact with the head skin in order to detect a brain wave signal. The detector body comprises a plurality of holder pieces for fixing at least one electrode, a bendable belt for coupling these holder pieces, and a device for adjusting the distance between the holder pieces.</p>
