An X-ray diagnosis apparatus according to an embodiment acquires a first X-ray image and a second X-ray image by using mutually-different radiation doses; acquires a third X-ray image based on X-rays radiated onto a region of interest of the subject and onto a region other than the region of interest in mutually-different radiation doses; obtains position information of the region of interest; and on a basis of the position information, generates a subtraction image by calculating a difference between the region of interest in the third X-ray image and a region corresponding to the region of interest in the first X-ray image and calculating a difference between the region other than the region of interest in the third X-ray image and a region corresponding to the region other than the region of interest in the second X-ray image.