An optical tomographic image forming method including: splitting low coherence light emitted from a light source is split into a measuring light and a reference light; forming an optical tomographic image of a measured object by detecting an interference light that is obtained by superposing reflected light, reflected from the measured object when the measuring light is irradiated onto the measured object via a condenser lens, and reflected light, reflected from a reference mirror, which is positioned a predetermined length of optical path away from the splitting position, when the reference light is irradiated onto the reference mirror, wherein the method further includes: inputting a refractive index of the measured object; correcting the tomographic image in accordance with the inputted refractive index of the measured object; and outputting the corrected tomographic image.