Abstract: An X-ray apparatus comprising a casing filled with an insulating gas, a high voltage transformer in said casing, an X-ray tube mounted to said casing and connected to said transformer, an X-ray shielding member attached to the wall of said X-ray tube and defining a window through which the X-rays radially emitted by said X-ray tube are released in a predetermined direction, and means defining an X-ray path through which said X-rays released through said window of said X-ray shielding member are directed so as not to be radiated on said insulating gas, whereby a reduction of the dielectric strength is prevented and the cooling efficiency is improved.