An X-ray photographing device (1) comprising a turning means (3) for turning an x-ray source (11) and an X-ray sensor (12) around a subject (K) is provided with an arcuate movement means (4) for arcuately moving the X-ray sensor (12) around an arcuate movement center axis (C2), and a control unit (8). The control unit (8) continuously performs a first photographing step for detecting an X-ray flux (L) while turning the X-ray sensor (12) in a first arcuate movement range (d1) around the arcuate movement center axis (C2) by the arcuate movement means (4), a shifting/turning step for shifting/turning an arcuate movement arm (2) around the subject (K) by the turning means (3), and a shifting/photographing step for detecting the X-ray flux (L) while turning the X-ray sensor (12) in a second arcuate movement range (d2) around the arcuate movement center axis (C2) by the arcuate movement means (4) in the state shifted from the first arcuate movement range (d1) by a very small angle in the shifting/turning step. This configuration enables the acquisition of a CT tomographic image using a vertically long and inexpensive X-ray photographing means, thereby enabling cost reduction.
