An X-ray intensity correction method makes the background uniform by adjusting a raster element and an X-ray diffractometer. An X-ray intensity correction method for correcting the intensity of diffracted X-rays includes the steps of focusing X-rays on a sample for correction placed at a gonio center, entering fluorescent X-rays excited by the focused X-rays into a raster element formed by polycapillaries and having a unique focal point, detecting the fluorescent X-rays having passed through the raster element; and adjusting the arrangement of the raster element so that the fluorescent X-rays can uniformly be detected regardless of the detecting position. Since fluorescent X-rays are used, it is possible to adjust the position of the raster element because if the focal point of the raster element coincides with the gonio center, the intensity becomes uniform regardless of the detected position.