1. An X-ray diagnosis apparatus comprising: processing circuitry configured: to sequentially generate X-ray images on the basis of X-rays radiated from an X-ray tube and passed through a subject, to detect, each time one of the X-ray images is generated, a position of a feature point of a stent retained in the subject on each of the X-ray images, to generate, each time the position of the feature point is detected, a correction image by performing correction processing for substantially matching up a position of a feature point detected on a first X-ray image and a position of a feature point detected on a second X-ray image that is an X-ray image generated after the first X-ray image, the correction processing being performed on the second X-ray image, to generate, each time the correction image is generated, an addition correction image obtained by adding together the correction image and at least one correction image generated before the correction image, and to perform control of displaying a moving image on which the stent is almost stationary being obtained by performing control of displaying, each time the addition correction image is generated, a newly generated addition correction image sequentially.