The invention relates to an apparatus for controlling the initialization of an X-ray detector, comprising: an extraction unit which extracts the pixel values of image data generated on the basis of incident X-rays; a summing unit which cumulatively sums up the number of the pixels, starting from the pixel having a larger pixel value; a selection unit which selects a pixel value in accordance with the number of pixels summed by the summing unit; and a control unit which controls a backlight radiation unit such that an amount of backlight corresponding to the selected pixel value can be radiated.