Loss of light is reduced in an examination for periodontal disease. A plurality of optical fibers are each held by holder so as to be freely movable independently along the direction of the optical axis. Since the optical fibers are each freely movable independently along the direction of the optical axis, light-emitting end faces of the optical fibers can be brought into close contact with a tooth or gum. Light reflected from the tooth and gum can be made to impinge on the optical fibers with reduced loss.
