An X-ray image diagnosis apparatus according to an embodiment includes: an image processing unit configured to create a synthesized image by synthesizing an X-ray image of a region of interest inside a given region and an X-ray image of a peripheral region excluding the region of interest in the given region, wherein when the region of interest is changed, the image processing unit acquires an X-ray image of a changed region which is in the region of interest before the change and is changed to the peripheral region, from the X-ray image of the region of interest before the change, and then superimposes the X-ray image of the changed region on the X-ray image of the peripheral region to create the synthesized image.