An optical tomograph obtains tomographic images by administering frequency analysis on an interference light beam formed by interference between a reflected light beam, which is a measuring light beam reflected by a measurement target, and a reference light beam. A tomographic data obtaining section obtains tomographic data to be used for optical path length adjustment each time that the position, onto which the measuring light beam is irradiated, is changed. An optical path length adjusting section adjusts the optical path length of one of the measuring light beam, the reflected light beam, and the reference light beam, based on the obtained tomographic data.
