The X-
ray generating device comprises an X-
ray generating tube and an X-
ray generating tube, comprising an insulating tube having a first open end and a second open end, a
cathode arranged to close the first open end of the insulating tube and comprising an
electron emission portion, and an
anode arranged to close the second open end and comprising a target generating X-rays upon collision of electrons from the
electron emission portion; a
driving circuit configured to drive the X-ray generating tube; and an accommodating container configured to accommodate the X-ray generating tube and the
driving circuit, in which the accommodating container has a third open end, and the X-ray generating tube is arranged to close the third open end, the accommodating container being filled with an insulating liquid, the accommodating container defines a first space storing the
driving circuit and a second space protruding from the first space and storing the X-ray generating tube, the accommodating container includes a protruding portion surrounding the second space, and one end of the second space forms a third open end, and an outer surface of the
cathode includes a cylindrical side surface, and a side surface of the
cathode is surrounded by a first member, and the first member is surrounded by a second member disposed between the first member and the accommodating container.