PURPOSE: To make it possible to determine a photographing plane without giving an uneasy feeling or a fear feeling to an examinee and without accompanying cost-up by providing a window only at a position just above a dome and a rotation controlling device stopping a light projector above the window when rotation of an X-rays tube is stopped.

CONSTITUTION: When photographing a certain photographing plane of an examinee 3 is finished, either one of a pair of light projectors 9a and 9b on both side of an X-rays tube 4 is controlled so as to be always stopped above a window 10 of a dome 8. Before photographing the next photographing plane, the photographing plane is determined by performing a light irradiation through the window 10 from the light projectors 9a and 9b under this condition. Then, this photographing plane is photographed by starting rotation of an X-rays photographing mechanism. As the window 10 is only provided just above the dome 8 and this window is covered by either one of a pair of the light projectors 9a and 9b, the rotation mechanism can not be seen from the examinee 3. Therefore, it is prevented to give an uneasy feeling or a fear feeling to the examinee 3 and in addition, as no special controlling mechanism is needed, cost-up is avoided.