An X-ray tube includes: a vacuum housing configured to include an internal space which is vacuum; a target unit configured to be disposed in the internal space, and include a target that generates an X-ray by using an electron beam incident therein, and a target support unit that supports the target, the X-ray generated by the target being transmitted through the target support unit; an X-ray emission window configured to be so provided as to face the target support unit, and seal an opening of the vacuum housing, the X-rays transmitted through the target support unit being transmitted through the X-ray emission window; an elastic member configured to press the target unit in such a direction as to approach the X-ray emission window; and a target shift unit configured to shift the target unit pressed by the elastic member in a direction crossing an incidence direction of the electron beam.