Provided is a holder which comprises at least two probe mount portions into which a light-transmitting probe for emitting light from the tip thereof or a light-receiving probe for receiving light through the tip thereof is inserted from above and is to be put on the head of a subject, the holder being characterized by further comprising: a linear backbone portion that extends in a first direction that is perpendicular to the above-described direction from above; and at least two linear branch portions that extend in a second direction that is perpendicular to the above-described direction from above and is different from the first direction, wherein the lower end portions of the probe mount portions protrude from the lower surface of the backbone portion or a branch portion and are tapered.