An X-ray image processing apparatus includes a storage unit, a transformed image generation unit, a scattered ray image generation unit, and a scattered ray reduced image generation unit. The storage unit stores a medical image. The transformed image generation unit generates a transformed image by transforming pixel values, of a plurality of pixel values constituting the medical image, which are higher than a reference value obtained based on a representative value of the plurality of pixel values into pixel values lower than the reference value. The scattered ray image generation unit generates a scattered ray image based on the transformed image and a scattering function. The scattered ray reduced image generation unit generates a scattered ray reduced image with reduced scattered rays by using the medical image and the scattered ray image.