A stereoscopic X-ray imaging apparatus includes: right and left X-ray tubes; a diaphragm unit in which right and left openings are formed through which X-rays radiated by the right and left X-ray tubes pass, respectively; an X-ray sensor on which the X-ray radiated by each of the right and left X-ray tubes is projected; a controller configured to control positions and sizes of the right and left openings; and right and left visible light sources configured to radiate a visible light to the X-ray sensor in the same area as each of the right and left X-ray tubes through each of the right and left openings. Spectra of the visible light emitted by the right and left visible light sources are different from each other.