An optical tomographic imaging apparatus capable of obtaining a high resolution tomographic image rapidly. In the apparatus, light beams having different wavelength ranges with portions of the ranges overlapping with each other are outputted from light source units, each of which is split into measuring and reference beams in each of the beam splitting units. A reflected beam reflected from a measuring object when the measuring beams are irradiated onto the measuring object is combined with the respective reference beams in the respective beam combining units, and a plurality of interference beams generated when the reflected beam is combined with the respective reference beams is detected in the respective interference light detection units, thereby interference signals are generated and a tomographic image is generated using the generated interference signals.