An optical tomographic image acquisition apparatus comprises a light source unit emitting light a light dividing device dividing the light from the unit into measurement light and reference light a projecting device arranged inside a tubular sheath to project the measurement light onto an object a combining device combining reflected light reflected from the object or the sheath and the reference light an interference light detecting device detecting interference light between the reflected light and the reference light an interference signal acquiring device acquiring an interference signal a tomographic image acquiring device acquiring an optical tomographic image and a reference position adjustment section detecting a sheath interference signal that is an interference signal of the reflected light reflected from the sheath from the interference signals and adjusts an optical tomographic image reference position as a reference to acquire the optical tomographic image based on the detected sheath interference signal.
