An optical tomographic imaging apparatus capable of obtaining a high resolution tomographic image rapidly. Light beams swept in wavelength intermittently and repeatedly within first and second wavelength ranges respectively are outputted simultaneously from a light source unit. If the wavelength of either one of the light beams is within a fifth wavelength range, the other light beam is not outputted. The first or second wavelength range includes at least a portion of the fifth wavelength range. Each light beam is split into measuring and reference beams by a coupler. Wavelengths of reflected beams from a measuring object when the measuring beams are irradiated on the object and the reference beams are divided by a WDM coupler. The reflected beams and reference beams are combined by an optical coupler, and each interference beam produced thereby is detected with respect to each light beam as an interference signal.