Provided is an X-ray imaging apparatus including an X-ray source to emit an X-ray onto a breast, a detector assembly configured to detect the X-ray transmitted through the breast, a compression paddle configured to compress the breast positioned on the detector assembly, a paddle manipulator configured to control the compression paddle according to a command, a degree-of-compression sensor configured to measure a degree of compression to which the breast is compressed by the compression paddle, and a pressure controller configured to supply a pressure corresponding to the measured degree of compression of the breast to the paddle manipulator.