To ensure the stable quantity of light with respect to the reflected light of the measuring light in the transmitting surface of a probe outer cylinder as the return light to an optical fiber.

This optical tomographic imaging apparatus includes a light path length adjusting means for adjusting the light path length of the reference light split from the light source light emitted from a light source part, the optical fiber on which the measuring light split from the light source light is incident, a lens for condensing the measuring light emitted from the optical fiber while deflecting the same, an optical probe equipped with the probe outer cylinder in which the optical fiber and the lens are arranged and which is provided with a transmitting surface capable of transmitting the measuring light, and a coherent light detecting means for detecting coherent light from the combined light of the reference light adjusted in light path length by the light path length adjusting means and the return light from the optical probe. An irregular uneven structure converting a part of the reflected light of the measuring light in the transmitting surface to scattered light is formed in the transmitting surface.