An X-ray imaging apparatus and a method for generating X-ray images are provided. The X-ray imaging apparatus includes an X-ray source configured to irradiate X-rays to a subject, and an X-ray detector configured to detect X-rays penetrating the subject, and generate a frame image including pieces of X-ray data for energy bands. The X-ray imaging apparatus further includes an image divider configured to divide the frame image into images of substances, using the pieces of the X-ray data, and an image generator configured to restore the frame image by performing motion compensation on an image of a first substance of the frame image, among the images of the substances of the frame image, and an image of the first substance of a previous frame image.