PURPOSE: To provide a continuous rotation type X-ray CT device which can start collecting data from a desired position.

CONSTITUTION: A first sensor comprising slits provided regularly through a rotary frame 4, a projector 12, and a receiver 13, and a second sensor comprising a shielding plate 15 and an optical sensor 16 detect the positions of an X-ray tube 1 and an X-ray detector 2 relative to a reference position (the X-ray tube 1 is vertically therebelow). The rotary frame 4 is rotated at constant speed, the start of data collection is ordered, and information about the positions of the X-ray tube 1 and the X-ray detector 2 when preparations for data collection are complete is added to data collected by a DAS 3, and the data are provided to an image processing portion 7. The image processing portion 7 specifies the angle of collection of collected data according to the information about the positions of the X-ray 1 and the X-ray detector 2 and to a predetermined sampling angle, and reconfigures an image.