In order to change a size of an imaging area of a tomographic image of an object to be inspected easily, an optical tomographic apparatus (200) is provided for acquiring a tomographic image of an object to be inspected, the optical tomographic apparatus including a control means (925) for controlling a measuring light path length changing means (900) to change an optical path length of measuring light in a case where the size of the imaging area of the tomographic image is changed, and for controlling a movable means for moving a focus lens for focusing the measuring light to the object to be inspected along an optical path to move the focus lens in association with the change in the optical path length of the measuring light.
