An X-ray generating apparatus includes an X-ray generating tube including an electron gun and a target configured to generate X-rays upon receiving an electron beam emitted from the electron gun, a deflector configured to deflect the electron beam, a driving circuit configured to apply an accelerating voltage between a cathode of the electron gun and the target, and an adjuster configured to adjust deflection of the electron beam by the deflector in accordance with the accelerating voltage or an amount of change in the accelerating voltage so as to reduce a change in incident position of the electron beam onto the target due to a change in the accelerating voltage.