Provided is an X-ray generator comprising a cathode for generating electrons; a rotating anode having a cylindrical electron impingement surface, an X-ray focal point being formed by a region in which the electrons impinge upon the electron impingement surface; and a Wehnelt electrode for imparting an electric field to the electrons emitted from the cathode. The Wehnelt electrode has a field formation surface for forming the electric field, and an electron passage aperture formed by the field formation surface. The field formation surface of the Wehnelt electrode is inclined with respect to a plane tangent to an outer circumferential surface of the rotating anode at the center of the X-ray focal point. The center of the cathode is in a plane orthogonal to the field formation surface and aligned with the center of the electron passage aperture.