1. An X-ray diagnosis apparatus comprising: an image generator that sequentially generates X-ray images based on X-rays emitted from an X-ray tube and transmitted through a subject; a detector that detects a position of a feature point in the sequentially generated X-ray images; a corrector that performs a correction process such that an angle of a line segment including a first position of the feature point and a position of a first single point based on the first position of the feature point detected in any one of the sequentially generated X-ray images substantially agree with an angle based on a second position of the feature point and a position of a second single point based on the second position of the feature point detected in a new X-ray image generated after the sequentially generated X-ray images, thereby sequentially generating corrected images in which a point different from the feature point in the images is located at substantially the same position; and a controller that, every time each of the corrected images is newly generated by the corrector, sequentially displays the corrected images, thereby displaying a moving image on a display.