An ocular depth dimension measurement apparatus capable of accurately obtaining an ocular depth dimension. The apparatus has a measurement light projecting optical system with a light source which is arranged to make a part of the light from the light source into first and second measurement light and collect the respective measurement light on first and second measurement surfaces of the eye, an interference optical system with a separation unit arranged to make the light into reference light and an optical path length changing unit which is arranged to synthesize the first and second measurement light respectively with the reference light to make them interfere with each other so as to photo-receive and obtain interference signals of the respective interference light, and a calculation part arranged to calculate the ocular depth dimension based on the interference signals and a driving result of the changing unit.
