PURPOSE: To accommodate an X-ray tube in its container without eccentricity and improve its insulation by integrating with the fixing section, an insulation cylinder section which is tilted along the inner face of a stator coil and insulates the gap toward the anode section of the X-ray tube.

CONSTITUTION: A stator 3 is arranged around the anode section 2A of a rotary anode X-ray tube 2 which is supported in a tube container 1 and an insulation cylinder 14 is installed between them. The insulation cylinder is toward into an integrated body by interposing insulators among its components consisting of its insulation cylindrical section, support cylindrical section 14B, and fixing section 14C, and a screw section 14A is provided on the external surface of an opening end in order to fix a stator retainer 6 with screws. As a result, when the X-ray tube 2 is fixed by the fixing section 14C, it can be mounted coaxially without eccentricity and with accuracy. Besides, since a stator lead passes through the insulator, the insulation of the X-ray tube can be improved. Also, the reliability can be improved, by preventing any damage, failure, etc. of the X-ray tube 2.