To provide an X-ray generation device which can change the focus where an electron beam collides with a target easily while maintaining X-ray dose.

A first deflection coil 11 and a second deflection coil 13 are installed at two stages along the axis A to unite a cathode 1 and the target 3. A collision position changing control part 21 changes the direction of the center orbit E of the electron beam e which enters into a throttle hole 8 by interlockingly operating these deflection coils 11, 13 while the center orbit E of the electron beam e passes through the throttle hole 8. By this, there is no possibility that the generated X-ray dose is reduced because the electron amount which passes through the throttle hole 8 and which arrives at the target 3 does not decrease. Furthermore, by making the direction of the center orbit E of the electron beam e which enters into the throttle hole 8 be changed, the position of the focus F can be changed easily and freely. Therefore, even if the focus is damaged, the position of the focus F can be changed easily.