In an X-ray imaging apparatus, which has a radiation source for generating radiation, and a detector for detecting the amount of radiation of the radiation, a subject is relatively rotated with respect to radiation which is radiated from the radiation source in the direction of the detector, and radiation amount data for image reconstruction is acquired in a predetermined rotation section. At this time, a desired observation direction perpendicular to the rotation axis in association with the subject is designated, and the position of the predetermined rotation section is determined on the basis of the designated observation direction.