In order to provide an X-ray CT apparatus and an image reconstruction method that can determine a movement phase to be used for generating diagnostic images with a small number of operations and can acquire diagnostic images in a short time while reducing a burden on an operator in scanning in which the target is a moving site, an image processing device 403 of an X-ray CT apparatus 1 obtains movement information of a diagnostic site (such as the heart), determines phase selection positions p1, p2, and . . . so that the operator selects an arbitrary movement phase based on the acquired movement information, and reconstructs selection images 80 in a plurality of movement phases (for example, 75% to 95% or the like) for each of the determined phase selection positions p1, p2, and . . . using scan data before presentation.
