PURPOSE: To enable an X-rays source apparatus to move up and down to any height and to any position by means of a small device, by winding a rope back and forth between a sheave provided on a supporting pedestal and a sheave attached to an arm on which an X-rays source apparatus is mounted.

CONSTITUTION: A supporting pedestal 12 is mounted on a stanchion 10 so as it may slide up and down, an arm 13 is arranged on the supporting pedestal 12, and an X-rays source apparatus 15 is attached on the free end of the arm 13. Furthermore, a sheave 17 is provided on the supporting pedestal 12, and a sheave 18 is provided movably also on the arm 13. A rope 21 is wound back and forth between the sheave 17 and the sheave 18, and a balance weight 23 is fixed on the other end of the rope. By these means, it is possible to move the supporting pedestal and the arm to any height and stop them there, and, moreover, it is also possible to make the X-rays source apparatus go up and down to any height on the arm.